I have a 95 Blazer LT. It's running at high idle. If I spray combustable fluid around the front part of top engine cover, after disconnecting one of the air hoses, it boggs down to low idle. Can anyone tell me if this means the plenum gasket is no good and needs to replaced, or should I still try and clean the TPS valve and the IAC.

 

Does this truck have the large aluminum plenum? If so then check the fuel lines in the rear of the intake, they have a tendency to crack and leak inside the plenum. These lines are available from NAPA and OReilly. TPS spec should be .5 volts at idle and 5 volts at full throttle. Check all major vacuum hoses also.

 

not sure.....it's a 4.3l vortec......I'm hoping cleaning the TPS sensor and IAC will fix the problem. Also, maybe the computer needs to be reset. If I disconnect the + and - leads from battery, let sit for a while, and then reconnect them, will this reset everything ???

 

check for gasket leak had same problem on 89 4.3 throtle body gasket leak telling comp to give more gas