Lets try again… hard to diagnose misfire/hard start issue on an 85T

I did do an injection cleaning service (Through a vacuum line) and ran plenty of injector cleaner through it, but that is very solid advise, that I will follow. Thank you both!

Okay, I got some stuff done today! I installed the new plug wires, (#4 and 6 SUCK to get to!) while making sure they all went to the correct places, installed/adjusted the new TPS (It helped), installed the new coil, and then the new Bosch O2 sensor. The car definitely runs noticeably better. The misfire at cruising went away almost completely, and was diminished under acceleration. I can actually drive it some now, I think. This does not mean fixed, though. It misfires especially while under boost, and just afterwards, then smooths out. Vacuum pressure at idle is about 15inhg. After revving it, it dips down to 20, then comes up to 15… vacuum leak?

Tomorrow, I will test the injectors, swap the distributor, and fix the exhaust leak. Here's where I need your help though:

1)I noticed the wastegate has an adjustment on the rod. What does this do/how do I adjust it? Would that contribute to my issues, since the downpipe and flapper valve is different?

2) I was also wondering if I need to use different vacuum lines for the turbo, due to the added heat in that area. I have silicone lines left over from when I redid all the other vacuum lines in the car, would those still work?

3) Lastly, I want to replace the rubber hose between the charge pipe and the intake manifold. What size is it? I was planning on ordering a reinforced one from the same site I bought my lines from.

The only other thing I was going to do is to replace both crankcase ventilation hoses, but I'm guessing I can only get those from the dealer. Mine are hard as a rock, and probably leak.

Drove a little longer today. Definitely still has the misfire, but it isn't as pronounced. It also starts better than it used to. I still need this fixed though… I have one month to get it through emissions!

the throttle body coupler should be 2 3/4"

have you verified ignition timing since all the recent updates?

what NGK plugs are you actually running? also - at what gap?

the vacuum doing that is negligible. as it makes sense going that low on closed throttle, and regaining for idle (the IAC opens).

I'd advise against messing with the wastegate rod.

Drove it about 40 miles or so, under different conditions today. It definitely runs much better when it's hot. All that progress I seemed to have made must have been at least partially climate related. Engine misfires under load, for sure, although it isn't consistent. Occasionally, it pulls smoothly under boost, most of the time though, it coughs and hacks. At lower speeds, while cruising, it runs smooth as silk.

In response to Axel kain:

I checked the timing again today, and it is perfect. Of course, that assumes my timing light is accurate. I may take it somewhere and borrow a timing light to verify.

I'm running NGK v-power plugs, set to .44 and brand new NGK wires. The plugs haven't changed from when it was running well.

I will still replace those lines since I'm sure it needs them anyway, but thank you!

My concern is we effectively did mess with that adjustment rod when we swapped downpipes. We also added thickness by using copper sealant. Do you still think that is okay?

I had another thought today… When we did the tranny swap, I'm not sure if we hooked up a ground cable… could that cause this? I may have installed one, but it was a crazy day, and may have forgotten. The old tranny had a somewhat small cable towards the back of the tranny. I know this has to be related to the tranny swap in some way, since the misfiring appeared immediately after we did it.

My only other thought was that I still have a small exhaust leak before the cat, and I don't know how that would effect how the car ran, but someone suggested it to me as a possible cause. (Due to less backpressure… sounds unlikely to me…)

Thanks again, I need other minds on this issue, as it was suggested earlier, I think my frustration is getting the better of me.

I found a video on how to adjust the tension on an internal wastegate rod. I may try this… It's free, and will put my mind at ease.

I'd still like to know if the silicone vac lines will work on the wastegate, or if I need something higher temp. If someone can answer that, I'd appreciate it!

I also have more info that may help diagnose this. I've driven it more, and noticed the car does NOT like it when I engine brake. That is, when I downshift and put the engine under load. As soon as I come to a stop, it stalls, and won't run right for a short time after restarting. I can pedal it to keep it going, but it misfires BADLY and won't respond to throttle. If I press the clutch in, and let it idle down normally, it idles fine, and aside from the constant small misfire, will run normally. This seems important to me, and may help diagnose this to someone with more experience than myself. This Tuesday I will be back to trying to repair this, and I want as many potential solutions/things to test as possible.

I ordered that intake coupling. Thank you for the size!

I also rented a fuel pressure tester from Autozone, and will be testing it shortly. I checked the ECU codes after putting some miles down, and got a few. Vehicle Speed Sense (speedo broken), Air conditioning (Not sure why, it works perfectly), neutral safety switch (Not hooked up), and most importantly: Fuel temperature sensor. I'm now back to suspecting the pressure regulator. The pump is new, but still could be faulty. I will test the resistance on the injectors, too. It sat for so long, one or more could be plugged, but I'm not sure if that will even show up.

PROBLEM SOLVED!!!!!

I found out why the ECU threw the "Fuel temperature sensor" code. The terminal was full of corrosion. Even though the sensor works perfectly (Well within spec) the signal never made it to the ECU. New terminal seems to have eliminated that fault. This didn't do a thing for the way the car ran, however, but did direct my attention to the FPR. After fixing the sensor, I tested the fuel pressure. I had to repair the shitty autozone rental so it would work, but once I did, it read 40psi… no matter what. Priming, idling, revving, all of it. Looks like the valve was jammed at a fixed position. No wonder it ran like shit! It was running rich most of the time, then lean under boost. Explains the awful gas mileage I was getting, too. So, I picked up a new one from Autozone for $60, put it in while still in the parking lot, and bam! Runs like a new car. It purrs at idle, revs smoothly, and the power is back!

Thanks to everyone who helped! I still have a mountain of work to do on the car, but this was my biggest stress source. It's hard to justify spending so much money on a car that barely runs, but now that it runs well, I feel better about it all.