1995 GMC SIerra not running well! HELP!?!?!?!?!?

[Tiffany]

1995 GMC Sierra 350 half ton. When I let off the gas thr RPM's drop to just about stalling then jump up again and idles around 500. I recently replaced throttle body and gasket. The RPM's were dropping and jumping before I replaced the throttle body and gasket.

 

[Duchamp]

Check the fuel pump! I had the same problem with a Suburban!

 

[Molson02536]

1995 GMC Sierra 350 half ton. When I let off the gas thr RPM's drop to just about stalling then jump up again and idles around 500. I recently replaced throttle body and gasket. The RPM's were dropping and jumping before I replaced the throttle body and gasket.

Inspect your IAC (idle air control) valve, it may be sticking from carbon deposit and if that's also new. Check the connections to make sure it's not biding buy spraying Throttle body cleaner through out your throttle body intake bore. AT worst, replace your IAC.

Start with that with also replacing your fuel filter, good luck and keep us posted.

 

[McCool]

IAC is a good bet, check the fuel pressure to be sure though.

What codes are the ECM throwing?

 

[dgbertrand]

I had a 95' GMC JIMMY and it did the same thing. It ended up being that there was dirt in the EGR valve and it caused it to do the same thing at idle. Didn't even have to replace the valve just took it out, cleaned it, put it back in and ran like normal. Worth a try if you even have an EGR valve on that engine, I'm not sure but would assume you do.