Hi, i bought a 91 camaro rs(tbi)the previous owner converted it from a 305 to a 350and messed somthing up. when i first bought the it ran fine but as time went on problems started and became worse. It idles fne but often the idle spikes up to 15-18000 until you shut offthe car. i dont no if this is related but sometimes the car starts to overheat. i replaces the computer and no change. a coad pops and it says ECM connection error. I dont no if its the prom chip or what.

 

I think maybe a vacuum leak?

dave w