1999 mercury cougar v6 5 speed
Discussion Starter · #1 ·
So for the past year I've been looking for what I feel is a none existent vaccum leak. I can rev it at a stop and it's fine for the most part. But when let's say I'm coming to a stop at the light the engine surges up and down in rpm from 3000k to what it should be about 800. And once I let off the brakes and are at a complete stop it idles perfect. But also does it when shift gears oddly enough.