Issue with 2012 Freightliner Cascadia

Hello everyone, I would like some help maybe if someone experienced the following or has any advice I would appreciate it. Onwards to the issue, I have a 2012 Freightliner Cascadia with a DD15 engine, that has about 650,000 miles on the truck and about 250,000 on the motor. The motor was replaced very recently with a used motor. Initially, after installing the motor the truck had a big oil leak which was repaired by replacing the o-rings on injector #s 3 and 4 and a seal in the air compressor. Afterwards, the truck seemed fine until I was on the freeway and it throws both of the check engine lights and the stop engine light. I pull over to check the dashboard diag and it had thrown 9 codes 6 of which were the injectors, the engine has 6 injectors and the computer shows that every single injector is bad along with 2 vehicle speed sensor codes and a position sensor code I think for the camshaft. The truck usually runs fine for maybe 1.5 hrs of continuous use from cold start. After the truck throws the codes I pull over to check and the truck shuts off. When I go to turn on the truck the lights return immediately after turning the engine on and requests to shut off the truck. If I rev the engine above 1000 rpm it will force a shutdown SOMETIMES, even if I am holding the shutdown override, other times it will allow me to keep trucking as long as I hold the shutdown override button on the dash, in other words, this is an intermittent condition, with a symptom, that is intermittent, within the bigger intermittent issue. If the truck allows me to keep trucking I do so but every 15-30 seconds the truck has a momentary jerk I am assuming that is the engine attempting to stop due to the stop engine light but doesn't because of the override switch or perhaps because I am moving. My mechanic has replaced the engine harness and the issue is still there. Every time this happens all of the codes above happen at the same time usually starts with the VSS code then piles on the injector codes and lastly the position sensor in that order every time. Has anyone ever experienced anything like this? If so what fixed the issue for you and if anyone has any advice it will not go unnoticed.
-Thank You

 

Thanks for your input I will pass the message to my mechanic and post what ends up working.