I have what seems to be a miss at low idle on #4 injector based on diag scan showing it not working at low idle. When reved to high idle it goes away on the diag on the laptop and sounds normal. Im thinking it could be the engine harness. Could it be the injector harness under the valve cover also. It seems electrical, could it be something else? Is there a good after market source for engine harness and injector harness? Eng ser 5ek96791. Also, cat part number of harness if anyone can look it up. Thanks.