My Cummins has started acting funny. If I get on a hill/steep grade when in 4th or 3rd...it just slows down to about 50 and won't downshift to speed up. I'm not sure if it's a tranny problem or what. It's not consistent either...some times it'll downshift and scoot right along. Torque converter? Fuel?

Any ides?

Truck is a '98 2500 2wd with 185k.

 

Possible Governor pressure solenoid valve sticking.

 

On my old Mercedes, it would be fuel filter. What is your fuel pressure during this?

 

I reset the APPS and it seems to be better...haven't been back on the interstate yet though.