Help needed from the cat Gurus

I had the base apart and steel line off, front and top fitting out of the head. Also blew air through the fuel rifle. No evidence of the snubber any where? Fuel line and junction at front of head are clear also. I agree with you on the timing. What baffles me is it will run as it should then almost like flipping a switch it acts up. I have load tested the power and grounds to th ecm also. When running in this condition @ 1400 rpm in pto if I toggled down 50 100 rpm it would leave. It seemed as if it were several cyls but I could not isolate any particular cylinder.
I will dive into the fuel system a bit more. I plan to use the bucket and submerge the return and check for air.

 

AFinally got a secondary timing sensor code. Will recheck timing calibration. I have often considered timing curve different from ful or off throttle, just the way it reacts. The engine acts up the instant the pedal changes, this is why the fuel supply has been suspect. It reacts to pedal input instantaneously, no lag or hesitation to start or end it.
Hopefully this timing issues will straighten it out.

 

Ok the latest. Wednesday set timing calibration. Had code 42 within 2 miles, stopped at a past cat tech's farm he and another past cat employees listened to it and both thought it is definitely timing. 1 even thought it is likely it's firing the injectors twice? I had both sensors brought out and replaced. Code 42 left about 1/2 hour after calibration and hasn't come back. Anyway replaced both sensors put 15 miles on it before it acted up. It's not quite as severe maybe and possibly not as frequent. Yesterday drove 35 miles before it started. I ran with both sensors disconnected at different times, it is worse with each unhooked than with both. So now I am up against trying to get the ecm reflashed by cat or else where and or try a different cam, I hate to think of putting in the same p/n cam.
I considered having the heavy haul put in, but this truck is long legged 55 mph@ 1100

 

Cam gear lash was at. 005. I think I have found the culprit. I believe that the owner of the truck and I have been the victim's of some unscrupulous business practices. I am 99% sure the cam was renumbered to reflect the correct part number. This is about all I want to disclose now. I have to get the engine back together and test drive it.
This is very disheartening for me as I have spent a lot of money with this supplier, due to prices and availability of parts.

 

Yes the cam was incorrectly marked. I believe it wae intentional, more to make the part sale. I am reasonably sure the thought was they are all the same. Thus the renumbering. I have been in contact with cat about this issue. Probably won't be much come of it, (big me little you). Tough lessons learned are the ones you never forget.
I would like to thank all who offered suggestions, problems like this can benefit all of us.