No start???

[C3pilot]

So this has me stumped.

2004 Silverado 3/4 ton 6.0L automatic 4x4 with 222k miles. Got this truck about 6 months ago for my son’s first truck. It ran and drove but needed some refreshing. Engine work so far.
-heads rebuilt by machine shop, we installed w/new gaskets and bolts.
-new knock sensors
-new intake gaskets
-cleaned the injectors
-new plugs and wires
-oil and filter
-exhaust manifolds machined flat w/new gm gaskets
Engine went back together, compression seemed good and consistent across all cylinders. Truck starts up fine and we’ve driven it several hundred miles. But, it’s still not running right. Seems like there’s a miss especially after it heats up, say after 5-10 miles driving.

I have no check engine lights on. It feels like it’s under powered and running rich, 11.9 mpg. I’ve pulled plug wires one at a time to see if I can find a dead cylinder with no luck. I’ve removed the exhaust heat shield and temped each cylinder exhaust manifold to see if I can find a cool running cylinder, no luck. I’ve checked for vacuum leaks, no luck. I suspect cats might be clogged but haven’t been able to get a good look at them yet.

So here’s what has me REALLY stumped. In trying to figure out what might be causing the rough running condition I pull/clean/reinstall the grounds on the frame and block. Grounds I pulled: driver side frame horn (2 wires), batt to engine block (1wire), under driver door (3 wires 2 bolts). I didn’t pull the wire behind the pass cylinder head initially. I try to start the truck and it WONT start!
Engine turns over but no start at all.

I’ve checked for spark, it’s there. I’ve checked the fuel pump, it’s good. It shows approximately 53psi on the prime and slightly higher during cranking. Battery has been removed and FULLY charged. I’ve tried starting in Park and neutral, no luck.

I’m looking for some suggestions. Anything that seems obvious that I’ve done/missed that I can check. I’ll try just about anything. I’m thinking at looking at the cam shaft sensor next.

Thx!
C3pilot