Seems to be the case Mike, I had a family friend who is an AMR ambulance mechanic even come by quick last night, he definitely checked all the fuel things I did and it is not that we definitely ruled out, the Idle air control valve was one thing I was thinking, because it seems to do what you said, ALSO put it in Drive, not Park, and it runs a little better?!

He thinks its a major vacuum leak he hears somewhere, although we sprayed around the plenum and intake and it didnt rev up while we had someone lightly holding the throttle open to keep from stalling. Going to check up on IAC and see if I can buy a part locally and start there. I'll let you know what happens when Im back in later today, thanks again for reply.

Well, Went to Autozone and got a new shiny IAC valve, the old one I pulled out looked all gunked up and black/carbony on the spring and valve (which is weird because nothing but air should be in here right?). Put that in, started car and it idled up high, came down and then seemed to run fine as I FINALLY fixed the issue, few minutes later, it died. Driving down my street it died twice too under light throttle. Barely able to start it up b giving it lot of gas then getting back to my drive way. If you look at pic so far now I have replaced the IAC valve, MAF Sensor, PCV valve, fuel pump, air filter, checked all fuses and grounds, checked for vacuum leaks around plenum.

The only slight problem remaining is the boot of the vacuum tube right in front of IAC valve, the tube goes back to another black cylindrical sensor near the firewall. That is taped up and has slight, tiny leak. I will fix that later in day when I find right elbow piece. So here'* a top down pic of all I did, can this possibly be an ECU problem?! My AMR mechanic friend will bring the good OBD II scanner later this week (mine only gets codes, no freeze data). Really running out of ideas here.

Would a bad TPS cause these symptoms? As in barely starting, stalling all the time, "giving it gas" tends to help keep it alive. This is the only sensor I forget to look at, and no one has mentioned it yet to me, I know its job is to guess where the throttle is and talk to the ECU along w the other sensors for adjusting fuel/air ratio....would a bad one lead to such catastrophic problems?

Have you replaced the fuel filter? The throttle body may need cleaning !
Here is a way to diagnose the TPS :https://www.gmforum.com/trouble-shoo...sensor-279319/

Thanks soft, bought a multimeter weeks ago, guess I can try its maiden voyage now. I will try that for TPS,and see if thats culprit.

I have fuel filter on me, just haven't installed yet since I need a lift and unfortunately for a 13$ piece I'll need my mechanic to do that snap inline filter... so no that hasn't been done yet but old one is only 20k miles old, not the newest but certainly not ancient. I will probably have that done during week, whether I can fix this other problem or not


BTW I had 97 gold Buick just like yours, 3.8 as well. Wish I didn't sell her year ago, could be using her as backup now! Even though the gauges were all whacky lol

Man Im starting to lose patience. I just tested reference voltage for the TPS connector and got 5 V as expected. Even bought a TPS at Autozone installed for hell of it, nothing changed at all, Im returning that piece. So far...new MAF, IAC valve, PCV, ruled out TPS w new one, new fuel pump. Sometimes it tends to idle better when put into Drive even though Im going no where, as opposed to in Park w the auto trans??? BTW what is this vacuum piece? It plugs into the throttle body between the IAC and TPS, as you can see the boot was taped by someone other than me (black electrical tape) and is a source of a tiny leak in my opinion, Im going to have to find new elbow....but what is the part in the back that the other end connects into?? a black cylindrical piece near firewall, EGR or something? Any chance that would be giving me problems. Im out of ideas officially now guys, not driveable because it always stalls eventually, can't really even make it down my street.

Heres pic of the vacuum hose that goes from that black cylinder in back to the throttle body

Super limited info on it, appears this line may be part of throttle body coolant line? I never even knew coolant fluid ever gets sent around the jacket of throttle bodies, never heard of this in any car. That cant be giving me these problems can it?

Sorry for so many posts, Im learning as I go along here... it appears in Haynes manual that is part of the Evap Emmissions control system (EECS) that black cylinder must be EVAP purge control solenoid...shouldn't affect the engine badly like this, so I guess we can rule that out as well?