Anybody got suggestions on which part would need replacement?

My first thought is the cruise control wand might be bad.

 

New wand came in, ACDelco unit cost ~200. Looks real nice and all the buttons work crisp.

Installing tomorrow. Will update results.

 

That was not the problem.

FSD was just recently replaced from a bad Stanadyne "bulletproof" to a black one.

Black one has been working fine, but someone told me that could be a sign of a failing FSD. What's new with these things, eh?

Changing the break light switch today. I have a new Stanadyne on standby to test also.

Will update results.

 

That was not the problem either.

Looks like I will be swapping out the FSD with a new unit. The black one is not shutting off the truck, but if that works then I will use the black one as the spare.