lack of power, bad fuel mileage d12d. bad EPG valve?

Lately I`ve discovered that I don`t have pulling power, especially when going uphill. It goes away and comes back, but last few days it is really bad. No pulling power, bad fuel mileage (but not horrible) about 5,5 mpg. Now my engine brake is just like my pulling power. Mostly very weak, sometimes not responding at all and very rare it is fully operational. Mechanic with not a lot experience with Volvo engines figured today that my EPG valve is dead (silver small plate on driver side) It is actually not releasing any air when he uses air compressor to send air through it. Now, Is that normal or that means that EPG valve is dead? Repairable or not? After browsing here seems like that is common problem on a Volvo and I did run on a bad fuel few months ago in NJ (actually horrible fuel) that clogged my fuel filters in a matter of seconds no matter how often I replaced them. Pablo wrote that bad fuel can damage EPG valve... I have a feeling when I drive that something is choking engine , maybe engine brake because of the bad EPG valve? btw how do you know that you need to replace boost sensor? any symptoms?

Thanks

 

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As you can see pictures. Anyway, EPG valve was replaced. Mechanic found the airline coming from epg valve to exhaust pressure governor broken so that`s how he started inspecting all of this. EPG valve did not release any air through itself when put on a compressor (reason for replacement) We tested the truck after that but still same problem. Then exhaust pressure governor was taken out and result you can see on pictures. Piston doesn`t retract all the way back when no pressure and we had to use a crow bar to put it all the way back. We assume that`s what is chocking the engine. Cleaning sounds like the plan. Keep you updated!

 

btw, where is boost sensor exactly located?

 

Engine brake not problem... not EPG valve nor EPG (engine runs smoother and sounds like a Volvo now) Hunt is about to be continued tomorrow. Suspects: boost sensor and air filter. Any ideas?