Running fine then starting choking above idle

[jmark06]

I've serached some, but I'm in a hruuy cause my car is broken down in a neighborhood about 15 min away and I need to get it out of there today if possible. I was driving my 280z (I rebuilt an 82 turbo engine, using MS1 v3.0, stock dizzy, firing with internal VB... and stock coil, supra 440cc injectors, walb 255 fuel pump, aeromotive FPR, JSK O-ring rail) and it was runing fine for about 30 min. I got on it a little a couple of times only to about 4 or 5 psi boost and it did fine. Then one time when I got on it some, maybe 2 or 3 psi it starting choking when I slowed down. I pulled over and it idled fine. Whenever I got over about 1000 rpm though it started coughing bad. I had to get someone to come pick me up cause it was dark and I had no tools or computer. Today I went back and hooked my computer up to it. Still cranks OK and idles fine at 600-700 rpms. But when I open the throttle up, even slowly it coughs badly after about 1000rpms and never gets better. It runs into the 18+ air:fuel. I checked both the pre and post pump fuel filters and they seem fine. The pump seems to be working OK, but I haven't really tested it. I have constant 38 psi pressure at idle but when it starts to cough the pressure drops off some. I checked the spark with a timing light and everything looked fine. I just don't know what could have happened to cause this all of a sudden. I pulled each plug wire individually and it sounded like all 6 cylinders are firing at least at idle. Nothing seems weird with the megasquirt except Q1 and Q5 are not bolted down to the heat sink. They don't appear to be fried though, but maybe I can't see it. I guess they weren't bolted down before, but I really don't remember, I don;t knwo how they would have just popped up though if they were. My req fuel is 7.1, inj opening time 1.1, PWM current 20%, and PWM time threshold 1.1. None of these settings have changed since it was running fine. Any ideas?

[mobythevan]

The fuel pressure should be rising as you give it throttle, so seeing it drop off doesn't sound right(even if it only drops a little bit). Sounds quite a bit like my car when the stock FPR was bad.

[jmark06]

Well the pressure rises a little before it starts coughing and then drops when it coughs but hen shoots back up. The inj banks light up on the stim board so it seems like everything is working properly. I'm guessing that if Q1 and Q5 were fried that the injectors wouldn't fire at all. Is there anything in the computer that could cause this, no settings have changed. If the VB921 was fried it wouldn't fire at all right? I checked cylinder 1 with a timing light again and it seemed sparatic when I opened the throttle up some, but I don't know if that was caused by the coughing or the spark itself. Could the 30 year old coil be the problem? It was running perfectly one minute and then terribly the next. I could be wrong but it seems to be getting worse, like even the idle struggles a little and now even 800 rpms coughs badly. The AFR is showing 16 at adle and 19+ with any throttle at all.