Hesitation/Backfiring It hesitates and backfires shortly after starting but corrects itself once gas pedal is floored,.only to recur the next time the engine is started.

SOURCE: possible reasons for backfiring and hesitation while accelerating

Timing belt slipped.

SOURCE: have code p1391 and p0340, replaced both sensors

had similar problem with 99 ram. i made holes in crank sensor a bit bigger,removed rubber seal that sensor goes through in trans,installed 1 bolt and adjusted sensor back towards firewall and tightened that 1 bolt and its worked fine ever since

SOURCE: engine runs fine most of time then once in a while

It is best that you make a scanner to see if it gives you some code and do not keep changing parts for pleasure I recommend that if you measure the pressure of the gas pump when you feel the decision would be good for my doubts. Thanks