I have a 92 fullsize blazer that when at low rpm or when i let off the pedal tends to "chug". It doesnt stall, but the rpms sometimes dropps to zero and jumps back up. I have replaced spark plugs, wires, cap and rotor, coil, ICM, IAC, and TPS. Its not as often, but its still happening... Anyone have any suggestions?
Thanks

 

Have you replaced the coolant temperature sensor? If you smell the fumes coming out of the tailpipe while the truck is running, does it smell a bit like gas?

 

Yes it is running rich, would the coolant temp sensor cause that issue? If so how can I tell if its bad?
I also pulled the egr valve this morning and found out I'm getting blow-by when the valve is closed, considering replacing it too just to be safe.

 

The coolant temp sensor WOULD cause that issue. When it malfunctions, it tells the computer to dump in an extreme amount of fuel into the engine. I would replace it anyway as preventative maintenance as they fail frequently and can cause all sorts of odd problems. I would also replace the EGR valve just to rule that out.

 

Thanks, I will do that. I'll keep u posted on how its running.

 

Ok, sorrry its taken so long to reply. Since the last time I was on here, I have replaced the coolant temp sensor, egr valve, and intake gasket. The problem I had is gone, and my Blazer is running great! Thanks for the help!

 

Glad to have helped.