PontiacBonnevilleClub.com

Ok, I have an 02 bonneville. Problems; poor acceleration, 15-20 mpg drop, incline or no at 45-50 mph it sputters, with incline won't go over 55 mph, there is a weird sound like air being sucked or forced out from under the engine compartment while it's sputtering, it feels like the car is being pulled back when this is happening(the best way I can describe it), the engine light flashes but no code is being stored.

Things I've done so far; replaced, plugs(iridium), wires(top of line), coil packs all three(top of line), fuel filter, TPS, 02 sensor, MAF sensor, and fuel pump. Oh and checked all vacuum lines and components.

I am at my wits end, and dead end at that. Does anyone have any other ideas of what it could be and if there is a way to diagnose said problem without having to keep throwing money at it like a chimp with darts? Thank you for reading and anything will help.

Clogged cat.

Not sure where you're at (emissions testing requirements), but high-flow cats are pretty inexpensive, and installation cost isn't too bad either. Probably have everything said and done under $250, and that's on the high end.

I checked thee exhaust flow and it was fine. So I had the emissions tested and the guy said it passed cleanly. I didn't get the numbers, but he said my cat is working as it should be.

What's the state of your UIM? What about the PCV valve?

Could it be the MAP sensor which sits on top of the pvc?

Check the fuel pressure. The fuel pressure regulator could be shot and letting pressure just blow by. It also could be leaking gas into the vacuum line attached to it. Pull that line off right after shutting the car off and sniff/feel for fuel in it.

MAF sensor unplug it see how it runs

EGR valve stuck open?

I am on MAF sensor 5 now... and 4 previous "NEW" never worked. You said you replaces the MAF? Was it OEM or Ebay "new defective"