I have had a problem with my Cummins. At 70mph or so it would act like it was out of fuel. A new filter did not help. A trip to the dealer including a legnthy stay with the end result being bad fuel. The Dealership did not provide me a sample of the fuel to take to the fuel station.
This is the first I have heard of bad fuel.
Is the dealership thinking I am as dumb as I look?

 

Entirely possible...

I got some "bad" fuel from the dealer when I first purchased the truck in 2001. They filled the tank with no. 2 fuel in December. The cold caused the fuel to wax up the filter. I purchased some power service and loaded the sucker up. Changed out the water separator. It seemed like it still took about 3 tanks to totally clear things up.

Purchase fuel from places with a good turnover. There are a lot of stations that have old, dirty, or out of season fuel out there.

Note to self: Next truck purchase (in 10 years) do not allow dealer to put more than 2 gal of fuel in truck

 

That is part of my worries, I always purchase fule from a truck stop on the south side of Indy. There are always a bunch of trucks fueling up there.