Hi guys, I have a 2002 3.7 6.0 automatic Ram 1500 p/u had a check engine light come on, diagnosed as the #4 spark plug misfire. Pulled the plug, alot of carbon build up on the on the #4. replaced wires and new plugs, drove one day, check engine light is back on still reading the same code. again #4 was full of carbon build up, flushed out engine with a little deisl fuel to break down sludge, replaced the #4 plug, same thing. also Truck runs with vibration at 55 mph and has a "thunk" sound most noticed in park at idle, dont think its a knock, sounds more like something is hitting, still have check engine light on and still reads #4. any ideas?

 

probably needs a new coil on the #4

 

Are you sure that only a new coil is needed?...

 

no, but it's a possibility. reset computer and see what happens. (if u haven't already...)