Truck wont start code 1391

Question

Started backfired and sputters  now wont start.

Answer 1

P1391 Intermittent loss of cam and crank

ECM is mostly the fault with this code, you can replace the crankshaft position sensor and retest, even if the camshaft position sensor is faulty the engine would still start, the fix here is try a new crankshaft position sensor , If p1391 is still settting a ECM is going to be the solution