I have a problem with my 95 4.3 Vortec Blazer? I had the Trnsmission re built not too long ago, and now i am having issues with what i believe is the TBS? You see my blazer turns off when i put it in drive, or when i turn on the AC? I was messing with the sensor the first time i had problems with it and i cleaned it and put it back on and it drove good for the first few hours, then the problem came back? So then i ordered one (used) and put it on, and it is still giving me the same problem? Any information as to why or what else it can be would be great! Thanks!

 

What sensor is that, the throttle position sensor or the Idle air control valve?
What is your RPO L35 or LB4 ?

 

I believe he is talking about the throttle position sensor.

martin, if you keep the idle up a bit with your foot when you put it into gear, does it stay running? How about when it returns to idle in gear? Does it do this more when the engine is cold or up to operating temperature?

You may want to pull the IAC (idle air control) valve and clean it and the bore it goes into. Sounds like the engine isn't controlling the idle speed properly.