2000 7.3L Bucking/Surging

[bkthompson6]

I have a 2000 7.3L PSD. While driving last week at highway speeds it would surge or buck, kind of like you took your foot off the throttle and then right back on it. it wouldn't do it with my foot off the throttle and it wouldn't do it when i would hammer it. Only when i would be trying to keep it at one speed. From what i read on here i figured CPS. I replaced the CPS with the black IH sensor. Figured that fixed it. I left for a road trip today and it started doing it again when i got on the highway. About an hour and a half into the drive it was doing it constantly and you could barely drive it. Same thing it wouldn't do it at idle or at WOT. Then i got into the next town and stopped at a light, i took off from the light and when i got to about 20-25mph the truck would buck really hard over and over and over 4-5 times. Sounded and felt to me like the torque converter engaging and disengaging. (like it normally does at around 40mph). Once i would get up to 30mph it seemed like it would stay engaged all the way to about 40mph and then you could feel it shift to O/D, but not as hard as it usually shifts. It continued to do this everytime i would stop and throttle through the 20-30mph zone, wether i did it slow or fast, the more throttle i had on the harder to would buck. Im not sure what this could be. Is my tranny failing? Any and all input is appreciated! Thanks guys!

-Brandon

[hitmanheutel]

Sounds similar to what my 99 is doing. Mine is a little more of a rough shudder between third and overdrive than utterly violent surge. If I punch it it is fine but constant speeds on the highway are near impossible. I cannot even begin to use the cruise control.