I have a 92 Grand Prix with a 3.1 liter V6. The alternator crapped out on me. I swapped it out. The new alt. works fine, but now the car runs terribly.

When you start the car, it usually dies immediately unless you keep your foot on the gas.

Going down the road, coasting, it dies.

When the car doesn't die at idle or coasting, it runs extremely rough, idling from 400 to 900 rpm.

It has a 4 speed automatic transmission.

Where should I begin looking?

Thank you.

 

bad or loose connection related to changing the alternator, or something you unplugged or bumped. might want to make sure the new alternator is putting out what ever it should be.

 

Strangest thing. After I posted my problem on the message board I fiddle farted around the house for about 30 minutes and went back out to try it.

For about a second it acted funny like it had before, then the idle shot up to 2000 rpm for a few moments, and then dropped to 1500 before idling smoothly at the normal rate.

Took it for a cruise and it acted fine.

Got home, waited for a little while, and now it started fine again. Since our other vehicle is getting transmission work, there's this car and my camaro. My wife is too short to be able to comfortably work the clutch in my car, so she just took the Pontiac.

So we'll see how it goes!

Oh, I didn't mention this earlier. The first alt. I put in the car worked for about 20 minutes then died. The car did the same thing for a few moments, then straightened out. I drove it, parked it for about 10 minutes and then got back in, and it acted similiar to the way it did this morning. Then the idle shot up to about 2000 like it just did this afternoon and it was fine since then, until I swapped out the alt. again.