I had the same misfire code on and off.. Changed the plugs.. Went away, came back.. Read somewhere it might be the intake manifold gasket.. Replaced that.. Went away, came back.. Cleared it with a trinity.. But I have an o2 sensor code in there, so I gotta keep checking to see if the misfire code comes back.. I'm gonna have to isolate the problem with swapping identical parts if the code is still there.. Keep me posted on your situation..