Random stalling and on and off misfires

[Wyatt sokolis]

So I have. 89 pioneer with the 4.0 and I did the high output head swap few years back and she’s been running strong until recently I decided to give her some more love and fix up my lighting and get my heater working ..anyway I got my lights and heater working great and drove it for about a week to and from work with no issues..then she randomly started to stall out on me ..I went threw checked all my wires and sensors did a tune up and nothing ..I threw a fuel gage on her and she had good psi ..primed up to 40 then idles at 30 ( it bounces super fast around 32 to 30 psi )..I replaced the regulator and didn’t seem to help any .. started to check my injectors only to find out that I had a bad o ring suckin in air ..I replaced those and she sounded healthy!! Went for a test drive and I could feel the power gain !! And it did good for about 10 miles then of coarse my clutch master cylinder took a crap .. replaced that and took her back out and it was driving great but then boom she starts cutting out and trying to stall out on me again ..let it sit over night then on cold start it was misfiring like crazy !! As I went to go get my fuel and vac gage she smoothed herself out and now she cranks over with no misfire at a cold start ...I have been throwing the parts cannon at her for awhile now and really could use some helpful tips on what is buggin her ..things I’ve tryed is fuel pump and filter .. fuel regulator..new map sensor..new tps .. new iac...cleaned the throttle body..new crank sensor...new plugs n wires ..checked for vac leaks witch I have none and the valves are working perfectly still ...motor has around 20k on the rebuild and it is a renix block bored  .30 over with the 93 h.o head and set up running on off my slightly modified 89 harness with my 89 ecu ..she’s been a strong runner for years until now someone help me out !! Also she has always had a long crank time for starting up hot or cold 

[jdog]

type of plugs are you using?

have you checked the intake manifold bolts?

what all was swapped besides the head?

what fuel pump did you use?

 

[SVPete]

Recommend you read Dammerung's thread about 2/3 of the way down on this first page.

[MiNi Beast]

check harnesswires to coil. wiggle them then try starting.