Hi first time post here. My question is has anyone experienced power loss at 45mph excellerating to 55mph and the truck won't down shift out of OD once it hits 45 no matter how hard you get in it. Any ideas would be helpful and thanks for the input. Oh and I almost forgot to put its an early 1998 cummins 12v with 89,000miles on it stock except for flowmaster exhaust with no cat.

 

It could be an issue with the T.P.S, a loose TV cable, or a throttle linkage problem.

You can probe the orange wire w/blue stripe on the tps to check voltage. It should be around 1 volt at idle and around 3.5 volts at wot. I try to adjust them to 1.1-1.2 volts. For more adjustability you can ditch the T.P.S. and replace it with a potentiometer for less than $10.

To check the TV cablehave someone floor the pedal while you watch the lever on the tranny, with it floored you shouldn't be able to move the lever back much more than a 1/4".

IIRC Throttle linkage should measure 5" from the front pivot ball to the flat area of the bracket where the throttle/tv/speedo cable's clip in.

Brett