2008 Volvo D13 Missing on hard pull

I have a 2008 Volvo 780 D13 485HP. On flat ground it runs fine, but when it is put into a hard pull like going up hill it feel like it is missing. It will only do it between 1300-1500 RPMs when pulling a hill. When I start to pull a hill it will drop 5 mph instantly and have little power. The truck has been doing this occasionally for the last two months but getting worse. Today I have 23,000 lbs in the box and pulled Jellico at 25 mph and the truck missed. My mpg has dropped also.

I change fuel filters every 15,000 miles. Last week I changed them early hoping the problem was clogged fuel filters and put a jug of fuel treatment in the tanks. The filters had black liquid in them. I am still having the miss with the new fuel filters. There are no codes. I try to fuel at TA and Petro and try to avoid Bio Diesel, but the last couple of months I have had to get Bio twice and fuel at a Mom & Pop place once.

I had this same problem with a 2005 Western Star Detroit D13. I kept changing the fuel filters but it didn't seem to help so I traded it off.

What else can I try? Where in the diagnostics screen can I check for fuel pressure?

This truck has two fuel filters, the first is tall and the second is small with a plastic cup with a wiring harness and sensor on the bottom. It also has a pump that you use to fill the filters when you change them. To avoid using the pump I always fill the filter with fuel before I put them on. Last week I replaced the little cup and wiring harness because of bare wires.

 

So far it hasn't thrown a code. But it is bad enough that I am concerned about going out on the road.

 

When we bought the truck two years ago we were told it had been upgraded to the new cups. Did your truck show any codes? I assume you replaced the clogged sensors or is it some thing you can clean up.

 

When we bought the truck two years ago we were told that it had been upgraded to the new style cups. Did you replace the sensors and turbo actuator or are these something you can clean up.

Last year I had the Venturi? tube replaced because it was clogged. The mechanic said there was a known issue with it plugging up and said that it should be checked and cleaned after a certain amount of miles, I can not remember the amount. I wonder if this could be part of the problem?