03 6 L. missing under load
my o3 6 L. is missing under load . the problem started a couple of years ago.when towing 5 th wheel trailer under heavy load going around 65 mph the truck starts to miss. when i slow down slightly it would be ok. took to dealer when it was under warranty and they replaced egr valve. since then it has had 3 egrs. it seemed pretty good until last weekend. 1 st camping trip. started to miss really bad again doing it at all speeds. limped it for a while then stopped and uploaded a #4 power setting on my bd x tuner. was good after that for a few hundred miles then started to buck again. when you slow down its ok but as sosn as you put your foot into it again it starts bucking and misses. puff of black smoke after it bucks.any help greatly appreciated. has anybody got rid of their egr. thanks, strokkerman.