I'm located in basically grand junction Colorado. I put a new alternator plus battery's, replaced fuel canister for sensors. I cleaned oil,antifreeze,map and IAT sensors. Cleaned ECM ground just because and PCM plugs. I'm up and running... Not sure what even did it but so far so good. No voltage drops so far. May be you know how can you check crank sensor clearance without pulling the oil pan?

 

I think ive found someone who can help you. I'll be in contact with him, then I'll get back up with you. You'll have to have someone with a decent scan tool and a basic knowledge of powertrain control testing methods.

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Bad grounds seem to be a cause of alot of electrical problems with these trucks. I believe they call it a dirty ground. When the terminals or ground wire become corroded or even disrupted they find an alternate route for ground, pass of least resistance.