I had a similar problem but is was on #3. I found that the coil had a very fine crack where it connected to the spark plug and as it heated up the crack would expand causing a poor connection to the plug and a miss fire.

I ended up replacing the coil. Problem solved.

#4 uses a plug wire, but you could still have a crack at the coil or a bad plug. Try swapping the coil and plug wires with #1 and #2 to see if the problem moves to another cylinder.

Logansportage <img src="/forums/images/graemlins/patriot.gif" alt="" />

White 1998 4 door KIA Sportage 4x4 w/Eibach 2.5 spring lift and TJ rear coils, 4crawler 1.5 body lift, Monroe Sensa.trac shocks, Bosch 4+ plugs, Eaton LSD, 31x10.5x15 BFG KM tires, 2.5 cat back exhaust w/SpinTech muffler