I recently performed a tuneup consisting of plugs, wires, cap and rotor. Now the engine seems to shake like a vacuum leak, but I cant seem to find one. Do you think it could be the coil since I did not replace it. There are no codes except once an a while a o2 sensor code. It just seems like all the powers not there an sluggish. Its driving me crazy, I just dont want to keep throwing parts on it not knowing.