1996 dodge ram 2500 5.9 stupid check engine light is on so i plug in the scan tool and its tells me code p1391 los of cam or crank. who knows what that means. when its really cold it will start but will not stay running unless i give it gas for about 30 sec. then it warms up and runs great. but sometimes when the rpms or up hi 3500 then when i let of the gas i get a couple backfires like have a popcorn bag under the hood. thank you to anyone who can help me

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It's getting an intermittent signal either to or from the cam or crank.

 

im starting to hate my truck went out and but a new camshaft pos sensor and installed it the truck dosnt start with new one in so i thought i had a bad part so got another new one and still dosnt start but when i put the old one in it runs ok but i still get the check engine light . i have erased the code but it always comes right back somone please help

 

I have the same problem right now as I just rebuilt my engine. It's either dirty connections at the distributor where it plugs to the CKP, or the CKP is too far from the flywheel and has trouble reading the points when the flywheel cranks by.