About 10k miles ago my car was in need of a tune up and was running real rough so i changed plugs/wires, cap, rotor. I also needed a new cat so i put a new one on with a new o2 sensor and it ran fine for a bit. Later on it had a rough idle again so i clened my iacv and then put a new fuel filter and it ran fine. Now it has a rough idle again but only sometimes any suggestion would be great

Car-99 ex with intake and header

Edit- we also checked timing and it was fine except when the distributor is 0 it runs rougher and when its advanced a little it runs better

 

anyone?

 

try running some injector cleaner.

 

awhile ago i did the ckf bypass trick cuz the cel was on for it i checked the wires and they were pulled out so i hooked them back up correctly and the cell for the ckf sensor is on now. could that be my problem?