I got a 88 xj. it runs great for 15 min or so. lol then it just loses power and wont rev. temp is 210, good oil press. new fuel pump, fuel filter, air filter, thermostat. dont know what the problem is. it just stops pulling when it gets warm. there is no water in the oil so i hope its not a blown head gasket. it doesnt leak anywhere. ANY IDEAS???

 

It is possible that the exhaust is restricted either cat or muffler,Have you done a compression check on it?

 

could be coil too or cap for that matter. when things get hot they expand. Like cracks in coils when they expand they loose power or a cracked cap will do the same

 

thanks guys. i will check those things out today.