Thread: Can't find the problem

I have been having troubles finding the problem with my 1999 Pontiac Grand Prix 3800 Series. It runs OK whenever I barely hit the gas but when I give it more it wants to dog down. It also will have a very rough idle and dies all the time. I dies when I'm at idle and when I'm driving down the road. I have been getting terrible gas mileage since this started. I have changed spark plugs and wires. I've changed an oxygen sensor that was bad and still nothing has changed. Could someone please tell what could be wrong with it.

does it seem to bog down when you get into the throttle heavily? have you checked to see if the cat is clogged?