I just inherited a '86 Camaro 2.8L Auto. I starts up Ok, goes to high idle...it seemms to drive Ok for the first 5 minutes, then it seems to lose power, but SES in Not on. What gives...

 

Once i bought a camaro and when i removed the plastic cover that covers the gauges the bulb for SES light was missing.
Check that too.

Do a complete tune-up.

Check for pluged up Cat.

Good luck.

 

MVF,

Even though there are no apparent codes displayed, you can scan for DTCs and may find something. At least it would assure you that the ECM is working and likely monitoring the engine.

As for the MIL lamp, you should see the lamp illuminate when you first turn on the ignition. Watch for the lamp while you turn the ignition ON. Do not crank at this time. The lamp should go on briefly, then off briefly, then turn back on and remain on until the engine is running. This MIL lamp "bounce" indicates that the ECM has passed some basic power-up self diagnostics, has a valid PROM installed, and has some expected inputs and outputs connected to it. If the lamp does nothing, you need to check into that first since the lamp may be your key to finding the problem(s).

 

The first thing I checked was the SES lite. It came on then goes off. I also gave it up complete tune up.