This will be a little long so I apologize...

Most everything had been checked that I can think of, lots of new parts and updates to try to get this thing reliable for my son. Why a 16 year old in 2023 wants a car this old I dont know, be he likes it and he is paying for it, so pops gonna try keep in on the road for him, lol.

This came up out of the blue after car has actually been running fine for about a year.
Fuel pressure is good, doesn't falter even when the sputtering happens. New injectors, fuel pressure regulator, most all sensors have been replaced, updated or checked.

Also I have scanner that can read live data, no codes are present. I do have a small vac leak around a pcv grommet that I can't seem to find a replacement part for, this is not the one for the actual pcv valve but a tube on the right side valve cover that feeds back into the breather tube.

Idle also changes when I spray around the smog pump hoses, which I found a little strange since I though this just blew into the exhaust system, not into the intake. So that's something Im not sure about.

Also I have repaired a lot of wiring from PO's hack jobs, so this could be an electrical issue but car charges the battery fine. The original alternator did go out and was replaced not too long before these issues popped up, so again could be an electrical thing.

Data shows it does go into closed loop but will sometimes revert to open loop even after car has fully warmed up and everything. Don't know if its supposed to do that or not, I'm no expert on how this works.

I know your not really supposed to do this but I also noticed it will die if you disconnect the battery so again I expect an electrical issue but not sure where to look next.

Any ideas would be appreciated.

 

Also noticed lots of changes in idle and voltage fluctuations with blinkers on, lights etc.

 

I’m not experienced enough to give any real advice (I’m not too much older than your son really) but I can tell you rock auto has the PCV grommet, you can get a GM genuine one for under $3. Could be the same part for both sides, but I’m not sure.

I read you said it’s charging fine, but might be worth replacing the battery if it’s old. I read on a thread around here a while back that changing the battery can help with troubleshooting weird electrical gremlins. Personally that was the case for me. I’m not sure where you’re located, but near me rural king sells batteries for these cars for ~$60 with a 5 year warranty. Beats the crap out of paying auto part store prices, it’s probably the same battery with a different sticker anyway.

Sorry I’m not much help or if that’s all stuff you already thought about