cuts out, no throttle response after injectors were replaced

replaced injectors a week ago, and replaced vacuum lines/fuel lines. Fixed a few vacuum leaks etc. Now, starting it up for the first time, i had a pretty good backfire. Afterwards, it would idle like crap and have poor throttle response. If i pinched off the return hose, it would run decent or If i unplug the MAF, it would run normally for the most part part. So i swapped in another MAF, and ran fine, for about a day. Now its returned with same issue. I can't even start it up barely, it just wants to idle at like 400-500 rpms. If i pinch off my return hose, it'll run better, and idle normally.

On start-up it may rev up to 1400 rpms (cold), but then a few seconds later it falls on its face, it sounds like i'm losing like 3 cylinders, gets very lopey. Heres what i got so far:

Timing: 15*
fuel pressure: 34psi at idle, 42 with regulator unhooked, and 60psi with return pinched off
no vacuum leaks found, i've sprayed right on injector/intake seals
no codes stored in the ECM
vacuum gauge is showing 10" when its running like garbage, and then around 20" when i pinch off the return.
Plug wires are hooked up correctly
If MAF is unplugged, will run 80-90% better, still has some slight hesitation (could be because of MAF fail-safe though)

Things of interest:
Removing upper plenum, the EGR tube developed a crack where it screws into exhaust manifold, so now i have an exhaust leak
I had the distributor upside down for a day or 2 when i was doing valve cover gaskets/refinishing (maybe CAS got oil or some shit in it?)
It ran good enough to drive before i fixed all the vacuum leaks and injectors

Yesterday, after i swapped in the MAF it ran fine for about 45min, on my way home from my friends. Had power, no missing, had the exhaust leak even then, and it ran fine, just sounded like crap. IT wasn't until i went to get some food, that it acted up in the drive thru.

Heres a video i took before i swapped in the Known good MAF, and its acting the same way now. When the video starts, i've already got the return line pinched off.

http://s1331.photobucket.com/user/St…d017d.mp4.html

The only other possibility would be injectors, but if that were case, why would it run good with MAF disconnected? And why would it run good with another MAF, and then suddenly stop running good? Doesn't make sense, normally injectors would be fairly consistent.

Any ideas would be appreciated, as this is my DD, and i'd really like to have it back on the road. To those of you who have dealt with bad CAS, does this sound like what you experience.

I realize now this may be in the wrong section of the forum. Move it if needed.