Thread: I have no idea, plz help

So, here it goes! I bought a 2000 Grand Prix in January of this year! For the last 2 - 3 months I have been having trouble with it & have put a lot of money into fixing it! It has 129,000 miles on it and I have done regular maintainace like oil changes, plugs & wires. I replaced the transmission at about 125,000 miles & the alternator just today.

So heres the problem..

When I am driving the car it will start slowing down & won't let me accelerate. The RPM's will jump & drop while this is happening & my check engine soon light flashes on and off. Then it will suddenly stop doing all that and drive perfectly. I have found that it does not do it when my heat is off. I have no idea what that has to do with it what so ever but it works for now! When all this is going on it also isn't throwing codes! Could it be a short in the electrical system or what?

I just need some help in determining what could be wrong!

Thanks a bunch!

crank sensor i would say

Thank You so much everyone! I will have the mechanic look specifically at those things!

Originally Posted by cerick08GP

Just for fun, my money is on the cat.

why would the cat make the tach jump up and down? the crank sensor controls the tach.

a clogged cat makes a car do all sorts of funny things... including stumbling rpm's and the check engine light flashing means misfires... also something a severly clogged cat can do. so it is just as possible as the cps

it could also be a mass air flow sensor