OK,
this is my second cavalier it is a 2.2lt and Yesterday the check engin light came on and my car has lost power and acceleration..and the gas milage has gotten horrible...I think it is either spark plugs or o2 sensor or maybe fuel filter and thoughts?

oh also when I was driving up hill the car started to lose speed

oh also when I was driving up hill the car started to lose speed

Without trying to sound condesending, have you checked the air filter?

Try plugs and leads if not and fuel filter, get the fuel pump tested if they don't work and put your hand over the exhaust tip and get someone to revs it and see if it blows your hand if not you have an exhst blockage prob cat!

Yeah I checked the air filter and It is fine I am having it tested today.

Get the code read. Your probably running rich and have a blocked cat and a failing O2 sensor.

well it is working now....It was a coil....but I put new plugs in and wires too..now it runs like new agian...I love my cav.....