have you checked your fuel filter, mine was cutting a little bit, i though it was the plugs, but it ws the fuel filter...

 

ok, i no wat a catalytic convertor is, and i no there not cheap... and my cats are fine.. there was water in my plug well. I didnt think he typed catalytic convertors .. cause he spelt it so bad

 

Is it water or coolant in the plug well?
If you had a cat problem the check engine light would come on and give you a cat efficientcy code.

If you have moisture in the plug wells the look at your plug wires. Let the car idle and slowly pull off each wire one at a time with shielded pliers and see if the spark jumps off the side of the boot, not the end but the side. If it does then you have a bad plug wire. Another easy one is if you pull off a wre and the engine's idle doesn't change (if you have a rough idle) then again you know you have bad wires and or plugs. If you asre not super or turbo charged then put the original plugs back in.

 

Check engine light? Any codes? O2 sensors possibly