Heading down to Alamo, TX last week I noticed the coach did not have the usual "git up and go" on the small hills. No chugging, no check engine light, just not the same. While visiting my friends in Alamo, I took the time to change the primary fuel filter after seeing some black stuff come out the bottom when I opened the sample valve. Put 300 miles on it after that and the coach runs like she should, which is great since I am in hill country now outside of San Antonio.
Be aware of how your coach is running and don't wait for trouble on something like lower than normal power. It can be as simple as a filter getting plugged up which you will notice on an incline. Modern diesel fuel is not very regulated so it is easy to get dirty fuel which will plug up your filters. That is what the filters are for anyway- to keep dirt and stuff out of our expensive engines. Keep spare filters with you and either learn to change them yourself or have them and tools with you so you can pay someone to change it for you if you cannot physically do it yourself. Hopefully this will save a lot of aggravation from check engine lights, road side break downs, etc...
Cya down the road.
^.^d
To add to Ted & Karen's post--If changing your filters doesn't fix the issue, if you have an older coach with the steel tank, like mine, you could be dealing with rust chips from the tank plugging your check valve and suction line.
I changed filters about 10 times, drained the fuel tank and put in new fuel and shock treated it with a Biocide. Nothing worked until replacing the check valve and flushing the suction/fuel line.