Thanks for this and I'm going to forward this to the mechanic so we don't miss any possibilities.

the security problem would be separate from the running. and the scanner has nothing to do with it. if you leave the key on for some time it rereads the ign and will sometimes clear intermittent ignition problems. when the passkey does activates it starts for a few seconds and then shuts off the injectors.

it sounds like you have separate running/starting issue, possibly the maf if you are getting codes for that

Thanks jwfirebird.....

We put a new MAF sensor on today and NO GO. So it wasn't that. The only thing left is the computer or a ground. A service bulletin said there is a computer ground on the back of the engine. Now to find it. Troubles started when I hit a bump.....yep, maybe the ground. More later.

Worse than expected:
One cylinder has 0 compression and one has 40lbs...the rest have 90.
We think that whatever was causing the miss just overstressed the engine, causing the
timing chain to jump which bent some push rods etc. Options are to fix the engine or put in a used one but then we'd still have the problem that caused the damage to the present one and no one could find what that problem is. I went to a dealer today and brought home an 05 Chev 2500HD with the same 6.0. Has 160,000 miles and could suffer the same plight down the road. What to do...what to do ??? Thanks to all who gave suggestions. I guess I have a scrap 03 GMC.

i never heard of any sbc or ls engine jumping the chain under normal circumstances even at 3-400k

Thanks JW.....

We'll probably never know as I don't intend to have it fixed...I'll try to buy another similar pickup so I'll have lots of parts to use or for sale. I've been quite assured that the problem was the ground wire behind the heads. There were service bulletins issued for that exact problem. Whether that put such a stress on the engine that the chain jumped is another question, but it happened while missing and around 2000rpms.

The rig I'm trying out from a dealer won't start this morning. Battery is charged and yet nothing. Not even a click...tapped the starter while wife tried to start...Nope, not that!! I'll check the connections. I think I'll go fishing and I don't even like to fish