I've got an 89 iroc 5.7. Out of the blue the car just started to run horribly. It stubles and shakes under power. Sounds like a miss but I pulled the wires individually but no change in the idle.Every once in a while I smell fuel but it smells like coleman fuel not gasoline. I had new wires plugs cap and rotor in it for a few months ran great. Friend of mine told me it could be ignition coil or module. changed both,still the same. Removed hypertech chip that previous owner had installed and replaced with stock. No change. I pulled the codes and it gave me a tps voltage code and a faulty ecm code. I adjusted the tps through info on the site,disconnected the battery to clear the codes. Started the car,still runs bad but it is only flashing 12. Any ideas?

 

Can you get a vacuum reading? Significant vacuum leaks will not necessarily set an error code, but can cause your symptoms. If there are no significant vacuum leaks present (including the brake booster, PCV, and EGR) think about testing the oxygen sensor.

 

Thanks for the info Vader,I'm off to do some testing.

 

C/ Converter clogged? Check tailpipes for potato!

 

Don't forget the HVAC control. Do you hear a hiss with the heat on? Common vacuum leak.