Noroots8

How much time should a shop charge for changing an egr and cooler on an 08 mp7?? how much should this cost?

I have an 08 gu813 with an mp7. It has dpf and about 14,000 hrs. It recently started pushing alot of black smoke under acceleration and occasionally it makes a popping noise (feel)with a momentary loss of power. It runs smooth but may be slight off on power. A questionable mechanic replaced one injector but this didn’t change anything. I believe he was fishing. I dont have a boost gauge.