Transmission Intermitently Jerks And Jumps At 45 Mph And Above

[fargomiller]

I am having issues with my suburban. When I am driving, my transmission sometimes jump and jerks. It seems like it is trying to downshift, I hear a audible clunck the suburban jerks then all returns to normal. A few moments later it might do it again. It only seems to happen while giving it gas trying to maintain a constent speed over 45 mph. I notice it mostly at round 50 - 55 mph. When it happens the rpms do remain constant. The problem is less noticable when using cruise control, maintaining a speed of less than 45 mph or giving it gas to speed up.

[wierdo124]

How many miles on the truck?

[fargomiller]

How many miles on the truck?

 

There are 235k on the body, 50k on the rebuilt engine and 40k on the rebuilt tranny.

[wierdo124]

I say throttle positioning sensor. That would screw up your shift points...