Ok, i have an 05 trailblazer 2WD LT with the I6. Its runs rough at idle weather stopped at a light or just starting it. Sometimes it will almost stall. It was leaking oil on the back 3 plugs. So, I the gasket replaced and replaced the plugs with factory. Had the fuel system cleaned professionally with the pressure system thing. I took it and had it checked for a miss and no miss. It to run more rough while in gear with the brake on. And no check engine light on.

 

Please help!

 

You say they did the fuel system but did they actually pull the throttle body and thoroughly clean that and then reset pcm ? In a very high number of cases it is usually a dirty throttle body that needs to be cleaned "or" they cleaned it but did not reset the pcm which would cause an issue also.Also make sure your air filter is clean.

 

I don't know if they cleaner the TB and I am pretty sure they didn't reset the PCM. Can I reset the PCM my self? Yea, the air filter is almost brand new.