1991 firebird formula 350 tpi stalls when put in gear
 

Idles fine, stalls when put into reverse or drive. Can give it throttle when putting into drive to get it going, but stalls out if stopping at a light. Found a few threads that were similar, but nothing that solved my problem.

[Update] Problem fixed for anyone with a similar issue. Apparently it was a wire messed up in the wiring harness. Not exactly sure which since I was not the one who fixed it. Just what I was told.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

Sounds like the idle air control valve, if you give it a slight amount of gas pedal before you put it into gear does it stay running? if so that is typically the IAC, if it still stalls then it may be something with the timing advance.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

It stalls in gear if you let it idle.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

Right but if you maintain 800 rpm in gear by pressing the brake and the gas pedal will it stay running. Or does it feel like it's trying to move forward?

If it seems to behave holding it at 800 rpm then IAC, if it is trying to do a burnout doing this then torque converter, if it sits there but runs roughly or dies timing.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

Looked into this more and found people saying the torque converter gets information from the vss. I didn't think it was related, but my speedometer stopped working the same time I noticed this issue. From what I understand the speedometer, cruise control, and the torque converter get affected by the vss? I'm not able to test cruise control because the car is at a shop. I'm just looking for answers to hopefully understand what's happening with my car. I don't recall a check engine light coming on though... I read if there's an issue with the vss it'd cause it to.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

Could be the torque converter/lockup (tcc) but generally you can`t overcome that by giving it more throttle. Once it locks up no matter what you do when stopped it dies. But there is usually a tcc fuse you can pull or a electrical connector on the tranny for the lockup signal you can pull to test.

I`m leaning more to the IAC or or timing (or both) as others mentioned. A sticking or wrongly connected EGR is also a possibility. Other things like a clogged cat or bad fuel pressure (FPR) or a clogged fuel filter could play a part but you would typically see higher RPM issues as well which I did not see mentioned.

Hope that helps

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

Would a bad vehicle speed sensor cause it to stall when put into gear? I don't believe it's the torque converter.

Re: 1991 firebird formula 350 tpi stalls when put in gear
 

The torque converter failing would be a bit odd, the torque converter solenoid in the transmission going bad is fairly common. You can eliminate the TCC solenoid from the list of possibilities by unplugging the plug with pink/purple wires from the brake light switch, or IIRC pull the fuse. From what I remember (it was 20 years ago) when the TCC solenoid in my 3.1 Firebird went bad, it'd die coming to a stop. Which is pretty much exactly what my 86 T/A did when it had a cruddy IAC. Incidentally, I drove that same Firebird with the VSS shot for months without a problem.