avenger454

Curious as to just what the computer does while running in diagnostic mode. What is differant in how it treats sensor inputs, advances timing etc.

Here is the background on why. I'm having a problem with a 1995 Mercury Tracer. At first it started lacking power then got much worse. Right now it starts up fine, when you rev the engine it is very sluggish, if you put it in gear (auto) it doesn't want to rev at all, you can put your foot to the floor and it isn't enough power to move it. Heres the odd part, if I put it in diagnostic mode the engine revs like normal but I cant exactly drive around in diagnostic mode. Everythign I can easily test functions fine, and she throws no bad codes in diag. mode. I've checked the timing belt, but cant check the ignition timing because it's a DIS. Anyone have any thoughts?