I have an 01 E250 with the #4 cylinder missfire code. I too have changed the plugs and wires but to no avail. I've been running techron injector cleaner and it hasn't helped either. The engine seems to run fine . I'd like to try the seafoam into the intake line. Does it work? And are we talking the fuel line from the tank?Could someone explane how to do that to an idiot? I'm mechanical but not a mechanic. .

 

How about swapping coils and see if the problem moves?

 

Thanks for the idea Dave, I'll give it a shot.

 

The instructions on how to use SeaFoam are printed on the can.