our 04 pac started running real rough and tapping (sounds like valves) while my wife was driving yesterday, when I went to pick it up it would barely pull up on the trailer. It has oil, water, all belts and hoses in place. recently replaced plugs and #6 coil pak. anybody have any thoughts, I'm going to check compression tonight and run a scan on it, but the loss of power and rough running have me baffled