P0205 driving me NUTS!

Need some ideas as to where to go next. I have been getting a P0205 code and have tried just about everything I can think of to fix it. I'll start with a little history. It is a 98 XJ 4.0L Auto. I purchased the Jeep with a bad engine (cracked head & hole in #1 piston). Replaced the engine several months ago. Ran like a top untill a couple of weeks ago. I was on the interstate when it started missing bad along with a MIL. Once off the highway the miss went away until each time I stopped at a light and idled for more than a few seconds. Once I started moving the miss would go away. Got home and hooked up the scanner, it showed a P0205 code. Cleared the code and it was fine. Next morning on the way to work, less than a mile drive, the light came on again. This time no miss just a light. Got to work and pulled up AllData. Figured try the easy stuff first followed by the cheap stuff.
Heres whats been done:
1> Removed and blew out plugs on #5 injector, TPS & PCM
2> new #5 injector
3> new TPS
4> swap out PCM with a known good (from my other 98 4.0L auto)
5> check continuity on injector #5 wires to PCM
None of this worked. Within a few miles the light returns.

I have noticed that the Jeep runs perfect until it gets up to temp. Once up to temp the miss comes back while at idle in drive and at highway speed. Around town as long as im moving its smooth as silk. Im thinking maybe a bad ground that only goes bad with heat??? Maybe a break in a wire that only shows up with the heat??? Hell at this point im open to suggestions.