If its misfiring on one cylinder only and only at certain times not the rest, then it has to be something with that particular cylinder or path of spark travel.

1) You didn't mention repalcing the distributor cap?
2) You could have low compression.
3) One of the valves could be sticking open.
4) Are somehow fouling that spark plug i.e. fuel injector staying open. Any gas or oil on the plug?
5) Or the oposite where injector is staying closed and no fuel is getting into the cylinder.

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

'89 Raider V6, AT, SAS'ed, Dana 44 front & rear, 5:38 gears, NP 231 T-case.
'97 Montero SR, cold weather package, 4.90 R&P, BATTLEZ suspension w/ 2" lift, JAOS grill guard & under body protection, custom rock sliders.