f-fish bite, but,..

under a hard pull the truck sometimes has had 2 quick hard fish bites in a row,. has happened 2-3 times in 3 months? starts great,. never misses a beat and doesn't always do the fish bite,..
of course i,m carrying a spare pmd like all good 6.5 owners,.
In the past,anytime i,ve had a pmd fail, its usually a few fishbites with a stall then game over,. this time it isn't dying?

can a fuel problem exhibit the same symptoms? Truck has plenty of power,.

thanks

Could be air intrusion under load. Put a clear hose on the IP return and look for bubbles while running