My question is, could it be a fuel pressure prob, or could this be because of the injectors I have in it, or perhaps the ECM/prom?

Here's what I have:
87 Iroc, 305 swapped with a 350 and is setup with TPI. However, something that is bothering me is, could it be the ECM? I say that because I'm still running the stock 305 ECM with the 350TPI setup. I have a 350 ECM, but I'm wondering if the chip from the 305 ECM would swap into the 350 ECM (I'm new on this kind of stuff). Or would it make any difference.

The only mod I did thus far was replace my stock 19lb injectors with 21lb. Would the ECM need to be tuned for this, or am I set to go? (injectors are already installed)

Here's the specs for more added info along with the link:
http://www.jegs.com/i/GM+Performance...99529/10002/-1


Specifications
Horsepower: 290 @ 5100 RPM
Torque: 326 ft/lbs @ 3750 RPM
Max Rec. RPM: 5100 RPM
Compression Ratio: 8.5:1
Heads: Cast Iron 76 cc
Camshaft Lift: Flat Tappet Duration @ .050" (222°Int/222° Exh)
Lifters: Flat Tappet
Connecting Rods: Powdered Metal
Block: 4-bolt main
Pistons & Pins: Aluminum
Crankshaft: Cast Iron Nodular, 3.480" Stroke
Rocker Arm: 1.5
Ignition Timing: 34° BTDC total advance
Fuel: 87 octane


Here's the problem I'm having, and I'm not quite sure what is causing it. I would like to get some opinions on this. Here's the whole timeline of what's been happening (I posted this in Tech/General Engine as well, but this might be a ECM related prob?)



I got my injectors swapped out a good week and a half ago, going from 19 to 21 lbs. The next night, I started driving about, driving for I would say a good hour, maybe close to two. I was driving, and the car had a slight chug, but I didn't pay much attention to it, as I kept going, and it seemed to be driving fine (or so that's what I was thinking). It did it again, but wasn't that noticable. I got home and parked the car.

A few days pass by, and I decide to paint some of the trim. I do that in about 2 days work and install everything on the 3rd day.

Friday comes by, and I decide to start the car (I had the car not start on me before because the battery was either bad or couldn't hold a charge? whatever the case, I got a new battery). The car cranked, but nothing. I did it again, and it fired up. I let it warm for a few minutes. Turn the car off, but I decide to try to try and start it up again to see if something is up (intuition is weird). I try, and it cranks, no start. I do this a few more times, and the last try or so, even pumped the pedal twice. Nothing, just crank.

Later on that night, I had a feeling the car would start up (weird, I know). I hop in, put the key in the ignition and turn. Crank. Try it again, It starts! I start pulling out of the driveway, and the car just kinda... dies. I start it up, having it start with the 2nd crank. I decide to go around the block since the car wasn't driven in almost a week. It seemed to drive just fine for the time being. I get home and park the car.

The next day (last Sat), I decide to take the car to the car wash (so automated ones, just a do it yourself kind). I did this because maybe this would of taken car of the squeal from the belt, as it may have had antifreeze on it from the injectors change.) I wash the car and under the hood (covered the altinator with a bag). I used some engine cleaner on it and rinsed after.

I hopped in the car and try to start it up. Just crank. Did it again, and it fires up, hearing the belt squeal (bleh guess that didn't fix the problem). I drive it around the block (car wash it bout 3-4 decently long blocks away from home). I start driving, heading toward the first stoplight on the way. I signal to the right and turn. I proceed to the next stoplight, then the car starts chuggin and dies on me (now I'm pretty much coasting to the light with the engine off, before breaking). I crank 3 times, and it fires up. I signal to the right again, and start heading back to the house. Along the way, the car starts chugging again, and I'm like "oh hell no, not this again," so I give it more gas, keeping the car alive, yet it still has the nasty chug to it. I get to my 2nd to last light (I was hoping for green, but I got red), and come to a stop. The car starts chugging again and wants to die on me. I can't run the light, so I mash on the brake and rev the car up, keeping it alive till the light turned green.

I start driving, this time in more of a hurry to get home instead of being stranded, I give the car more gas than usual (going bout 50 mph), still having the car doing the chug thing. I get to the last light, look both ways before turning and start back on the street to my house. I pull up in the driveway, and park it (it more like parked itself, as it died on me....)

That concludes the long story timeline, and most/all the details are there that I can recall of.

Random Note: since the change of the injectors, the car made a long squeal. It would do that for a period of time then stop, but something else I noticed was when I would turn the steering wheel either left or right, it would subside quicker. I asked friend about the stuff that's been happening, and he said it could of been the MSD. If it's loose, it could make the car run like crud as well. Same thing for a fuel leak, though when it was checked, there appeared to be no leaks at all.


Sorry for the long story, but I figure the more information, the better. Any help is greatly appreciated. I don't want to have to think about selling this car, as this has been a car I've always wanted in my childhood days