does anyone know what would cause a code 43? i have very poor gas mileage and it seems like its just not hitting on one cylinder or two, who knows.whould it be bad rings, worn out valve springs.
and if i change out the # 2 plug and clear the codes it runs better for a few hours then the 43 pops up again.runs like a champ when ever i give it some gas,but the idle sucks.

Multiple/ single cylinder misfire. If it has to do with your spark i would try a new wire and/or new coil pack. Normally when a misfire pops up its my coil pack. But it can also be valve problems. If its the number 2 try to compression check it for bad rings and/or valves. You are using the coppers or ngks? Alot of people say use champion copper but they seem to fault out on me often. Just remove each one of your spark plug wires one by one with it running to find out which cylinders are not firing. I had a buddy with a neon always had a #3 misfire. It always died. He changed the egr on it and it runs fine till this day.

If your cat is junk. Change it. The inside will come loose and go sideways, or kit will clog. And thats not good at all.

It appears as if by the op's aviator that he has a turbo... you are supposed to use 2 step colder plugs...

i already changed the EGR valve,put on new 9mm wires,new injectors. and all of the plugs do have fire to them.and i use reg.champion plugs.i checked the the coil pack and the secondary tested fine,but the primary was off a little from spec. i dont really remember what the number was i think it was like 0.8, spec is 0.45 to 0.65. dont know if that would cause a problem or not. i was thinking of putting a MSD coil on.or is there a better one out there that i can use? i am afraid its my rings or valve springs,dont know if they were ever changed on my car.and i know that neons had problems with the valve springs and carbon build up.just dont want it to be the rings[:@]