I have a 258 6 cyl in my 79 cj and im having a problem with it after it wrms up it backfires and dies sometimes. i had a intakeand carbarator leek but replaced gaskets and no more leaks. any idea what to look at next? it runs great at a cold temp???

sounds like your carb is flooding. if you want to reset the float without taking the carb apart. start engine and vice grip the rubber gas line while running. don't touch the throttle wait for engine to die take off vice grip then turn over to start.[this usually works to reset the float in the carb]

i had a similar problem. Two things that cause it for me were: 1. Timing was off. 2. The distributor points gap was off by just a few thousands. Other than that i would think you have a leak in your manifold, which you've already checked.