My '99 Xplorer is dying when run on roads at 40-45 mph, it will run all day in mud or trails but when I hold 3/4 throttle or so for 5-10 miles it will die, then need to sit awhile before it will restart. Plug is a nice brown, not too lean, no hot lights or coolant loss, timing is on, 135 psi compression cold, went through fuel system, draining and cleaning, replaced filter, replaced plug and plug cap, what else? A buddy said stator? Does that sound right?

Could be one or more of these things causing it. the carb jets are dirty or your needle valve is set to low keeping it from flowing fuel into the float bowl as fast as it is being burned out, could even be a bad vent on the gas tank, if it is kinked or shut off it will cause the tank to slow the fuel going into the carb, could be a blocked fuel filter, if it doesnt have an external one, some have one made into the petcock up in the tank.

Carb is clean, float level is good, vent is clear,new fuel filter, took the petcock off and cleaned it too, I've pretty much determined it's not fuel, I think spark

Its possible, the muffler might be a little stopped up..... try cleaning the insert if it has one.... if it aint the problem, it sure aint gonna hurt to clean it....

Mines doing the same thing i have been told coil is over heating or the muffler is plugged up still trying to figure out how to clean the inside. Bought new coil on ebay.