Quick run-down for everything. Truck was skipping with the check engine light on. Changed the injector harness. Check engine light went off, but truck still skips. Did injector cut-out test. #5 & 6 made no difference. Got a test ecm from another C10, skip is still there. Replaced all 6 injectors. Truck still skips. Replaced test ecm with rebuilt ecm, truck still skipping… Any thoughts??
Check fault codes. Maybe there’s a speed/timing issue? Check the valve train. Sometimes those camshaft followers turn sideways and eat the top of the cam lobes off. Or they just get wore out. Cut an oil filter open for a quick check.
Fuel system, filters, check fuel pressure. Fuel condition.
If it has engine brakes try swapping to another bank.