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Surging

hi. my car is surging. its an 85 fiero gt-2.8. I have replaced ALL the vacuum lines, plugs, wires, air filter. am going to change fuel filter as well, i just want to know if anyone has any other ideas on why this is happening. i run high octane and it has been re-chipped to performance. does anyone have any ideas? because after the fuel filter i am out of ideas.



thanks

Check for a vacuum leak at the intake manifold.

Tester

Please describe when surging occurs. Driving or idling? Trying to maintain constant speed?

ty for responding. the surging happens when trying to maintain constant speed, usually 25- 40 mph. does it bad after i have been driving it for a while. when at idle, there seems to be no problem. also when i accelerate hard, it doesn’t seem to have a problem either. someone mentioned vapor lock. does that fit? ty