Gazim,
I have a couple of current indicators. They are inexpensive little meters that you place over the battery cable and they measure current flow in the wire.
I got the last one at NAPA..Snap-On has them under the Blue Point name.
If your rig cranks with vigor when cold, but is very sluggish, almost scary, when hot, it would seem to me that it would either be the starter, or a engine issue.
If this is driving you nuts, I would take the truck to a automotive electrical shop and have THEM diagnose the problem.
You have done lots of things to solve the problem, but it persists. If it isn't the engine, which it doesn't sound like it is, then the only other heat sensitive device that plays into the 'start' scene is the starter.
I did a little research on this item last night, and found a site that gave this advice:
"pour a bucket of cold water on the starter and see if it spins over better when cooled"
I am not recommending this bizarre test, and I'm not sure Mr. Starter would work after the bath, but it sure as heck would isolate the problem.
Stuart
