I bought my tuck bout two months ago it a 99 cummins 2500. The rpm started jumping between 40 and 50 mph not sure why. I have heard some people say tps. Just checking to see if anyone has had this problem. Let me know thanks, jared

 

I am not sure but since your from chicago land area If you need parts from Cummins I get good deals From Cummins
but I dont think they have TPS on the engine its all done by the pedal witch I call tensionomiter/ accelorator pedal that is a dodge part
but if the Pedal is bad It will give you a CODE or wont accelorate at all
What happends above 50mph or below 40mph.
witch it maybe a trans problem at 45mph it changes to 4th gear?????? could be a valve sticking in your trans? causing it to slip????

 

Oh ok thanks it is normal below 40 and above 50 smooth shift fine just between 40 and 50 thanks

 

I think you have a trans problem some people have said check all the grounds and clean them first sounds good to me it don't cost anything but some time. maybe just a ground wire not making a good connection for a coil ground