Low boost/loss of power

[Mercmarquis]

I have an 09 F-350 4x4 long bed with a 6.4 diesel, all stock. I have just about 18K on the clock. I use my truck primarily for work and as a DD. I regularly tow my 33 foot travel trailer to and from job sites. A week or two ago I got a job out here in Wyoming. I checked all fluids, I drain the water seperator every month and loaded up the trailer and took off. 1600 miles one way. All through the trip from indiana through iowa the truck ran fine. Although it would regen about every 120 miles. When I got into Nebraska the truck ran really strong and my boost #'s were in the mid thirties or so. I was getting terrible fuel mileage at about 8mpg. I backed off some and just cruised to get better mpg. When I crossed into wyoming I noticed the truck was getting 12mpg towing but now it wouldnt boost past 27 or so psi. It seems down on power quite a bit and I struggle to get boost past 25psi. I'm wondering if this is due to altitude or what. I'm taking the truck in saturday for a fresh oil and its first fuel filter change. I'm hoping to regain the power and boost I had before. I'm not totally convinced that its due to altitude because I bought the truck in Denver in january and its ran great till now and remembered seeing 30 or so PSI of boost.

My thoughts are leading to either fuel filters not giving enough fuel or even a plugged up DPF causing too much back pressure to let the turbos spool. I'm really wanting to get a spartan and do the DPF delete but I wanted to rack up some miles first in case something went wrong on the truck and not have any issues with warranty. Does any one know if this is a common issue or any things I can do to diagnose it myself? If the fuel filter service doesnt fix things does anyone know of a reputable ford shop near Evanston or rock springs WY I can have it diagnosed at and hopefully get a rental car?

Thanks in advance for all the help!

Pete

[powerhoghp]

If it still regens then the filter is probably okay. Fuel filters would be a good place to look. Higher altitudes do make less boost and the truck reduces fueling to match, which gives the turbos less to spool with.