2003 Pontiac Gran Prix 3800V6Car is missing at 4000rpm and has lack of power afterwards.?

Question

Ran fine this am but when leaving work it would not upshift right. It would run up to about 4000-5000rpm then shift hard and then started to miss at 4000rpm on the drive home (interstate). When trying to pass it would downshift but not go. Checked all fluids, belts, and just filled up (at my work) and nothing noticeable. We have noticed a coolant smell for the past few weeks but there is no puddle under the car and the level seems fine. The coolant though is rusty colored but full. Car has 90,000 miles but never had a problem with it prior. Usually has plenty of get up and go but not now.

Answer 1

Could be starving for fuel, might want to check the fuel filter & the air cleaner. Try to look at all the simple things, so you want have to pay a mechanic to reattach a wire or something

Answer 2

You could actually have a transmission problem. But then again it sounds like you have some sort of ignition problem. Check all your Spark plugs and plug wires. Possibly change out your fuel filter. A lot of things can cause a miss.

Answer 3

i think it might have something to do with the electrics, maybe plugs or cable to the plugs, or the timing has sliped a notch, check your timing belt marks up right, or a crack in the disributar cap, thats where all the leads go for the plugs. but first just check that all the plugs are tight and the leads on to them ok

Answer 4

best that your trusted service center put it on their analyser. a coil pack may be breaking down at hi revs. Had an old 84 Pontiac Grand Prix, and the side of my coil busted off for some reason, and I experenced the same symptoms.

Answer 5

You have a restricted catalytic convertor. Just a guess. I'll put a $5 wager on it to the first taker.