I'm stumped....any thoughts?

[Beaver]

I have a cm2250.
I have done all the sensors (imap,delta-petc) but I'm still having turbo cough, low manifold pressure on acceleration and during jake braking and also my oil temp is sitting at 220 just driving on the flats.
When the motor is up to basic operating temp (oil temp at190) everything works great...well except I still have the turbo cough and that only happens when I'm stopped not when shifting gears.
Also when I stop the truck or 1st atart it up the turbo sits at about 5-7psi for about 5-8mins then calms back down.

I'm lost and frustrated. I had the oil cooler thermostat replaced, also my turbo actuator was bad so I did that. Not sure what I should check next

I have been going to the cummins dealer in Coburg, Or and they basically say..."no codes? Not able to diagnos"
Any thoughts would be a huge help!

Thanks in advance!