ISB 6.7 CM2150 problem

[Rawze]

(something to eliminate)...
same symptoms happen when the engine cannot breathe, especially the exhaust.

Disconnect the exhaust piping behind the turbo and if it runs and idles up significantly better.

next would be to also open up the exhaust manifold to let it breathe (before the turbo) and see if it runs and idles up significantly better, ensuring there is not excessive restriction from the turbo itself due to improper positioning. It can be done by removing the turbo mounting bolts and suspending the turbo so that there is a decent gap.

Also do a full EGR tune-up and replace the IMAP and other relevent sensors.. + ensure the egr valve is not stuck open.