Recently when towing with the Aspen (5000lb travel trailer), I noticed a new intermitent problem. When going up some steaper hills (hills that in the past were no problem to tow the camper up), the Aspen will all of a sudden lose power, and rev up kinda high. The sound/tone of the engine changes too. Sounds quieter and higher pitched. If I let off the gas and let the RPM's come way back down, you can hear the tone of the engine change again back down to a deeper fuller sound, and at that point i can get back on the gas and it has all the power back. Only occurs when going up steeper hills/mountain passes.

I'm guessing that it is either a tranmsission problem, or an MDS problem. I say that because honestly when it occurs, it actually feels like the MDS suddenly kicks in and the power loss and engine tone change is because it is trying to tow on just 4 cylinders instead of 8. I don't know if that is even possible though, but it kinda feels that way.

Anyone have any suggestions?

 

Hopefully you're towing with the transmission in tow mode, correct? Regardless, that sounds like your transmission is slipping. I haven't heard this one before. Please let us know what you find out.