this is my only car a 1992 oldsmobile eighty eight royalle
it doesnt like to go up hills it hesitates and backfires i replaced the mass air flow sensor the iat sensor the fuel filter the plugs and wires are only 3 months old what could my problem be

had the same problem myself, and went through EVERYTHING with a fine toothed comb. Nothing. Until I saw a bright blue SPARK jump when I was screwing around under the hood with it running one night. The plug wires I had bought 6 months ago were faulty.

Check your plugs and plug wires, even if you "know" they're good. Sounds a hell of a lot like the engine is firing the wrong cylinder at the wrong time (leaking high voltage).

i can relate.. before i changed out my plugs and wires, my car didnt wanna go at all... i thought they were fine, other wise i would have changed them sooner then i did.. def. check em out again.
-Joe

Sounds like the plug wires could be the problem; but, im going to go out on a limb and say it could be a very dirty air filter, just possably a thought. I know mine was pretty bad.

a dirty air filter shouldnt make the car backfire though... But its a good idea with high gas prices (VERY HIGH in Canada) to check the air filter

Heh, yeah I realized I forgot that part and just was too lazy to edit my post. A dirty air filter does reduce gas mileage and perfromance though..