I was driving to work the other day in my 1984 Camaro Z28 H.O. (all stock). I hadn't driven the car the past two days, and it was raining today.

About 5 mins after leaving my house the check engine light came on and when I let off the gas and had the clutch in the RPM's shot up to 2500 and slowly started increasing. I was just pulling up to a stop light and while waiting they went up to nearly 3000 RPM.

I decided to turn around and drive home to get my other car. A few seconds later the light shut off and the RPM's at idle dropped back to normal. I haven't experienced any reoccurance since. Any ideas what happened and what I should do to prevent it? I'm thinking something stuck on the carb. Maybe a rebuild is in order (it has other problems like blowing black on WOT and stalling during extreme braking so I should be doing that anyways). Wondering if there may be anything else that could cause this?

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1996 Camaro SS #C117
Former 3rd gens: 1985 Z28, 1987 GTA

 

The ECM has no capacity to change idle speed (aside from maybe kickin in the A/C compensator solenoid). It's is purely mechaincal stuff. Could be the choke linkage hanging up or something physically holding the throttle from closing again, but none of that should light a check engine light. I'd pop in a paper clip and see what code it spits out and post it here. It might help narrow down what could have gone wrong.