My CEL is flashing on and off on my 2001 Civic Ex. The code is P302 so cylinder #2 is misfiring. Changed spark plugs and coil and reset code. It was back on and flashing within a half hour drive. Also the cat sensor was sending a CEL code. I do not have a cat, and use a O2 sensor simulator. Any suggestions on how to fix the misfire?

Cap, rotor and plug wires replaced? Check the compression in the #2 cylinder also. Low compression will show as a misfire.

Compression is fine...No cap or rotor on this model.. I replaced the coils

When it idles it bounces around quite a bit...Up and down

Oh that's right, I didn't catch the 01, forgot they went coil on plug.

Check the plug to make sure you didn't crack it. Switch the coil with #3 to see if the misfire moves to that cylinder. If it doesn't the only other thing is a bad injector.