I have a 119 engine with 63K miles on it. It started running with a rough idle after I had it steam cleaned. I've had the engine mounts replaced, as well as the wiring harness and throttle body (fault codes indicated a problem). There are no fault codes... but still a rough idle. It feels like a misfire, but no codes to indicate it. The timing and voltage for each of the cylinders seem equal. Is this possibly spark plug wires also?