So I got one from dorman and it worked for about two months now its back to shuttering between 30-40 mph. But only when truck is cold, Kinda weird. But I can't find an oem unit on ebay or anywhere, does anyone know of a site to go to find one? These things are a pain!

 

I am not sure the shuddering would have anything to do with the TPS. Maybe someone else will chime in, but my experience has been that they either work or they don't.

 

I use rockauto.com or amparts.com for online parts. I have to agree that your issue doesn't sound like a tps or cps.

 

^^^^^ +1; to pin it on the pedal position sensor, you'd have to get a live feed of its value (volts or percent) at the time you get the shudder. Something like AE that will log the value over time would be of use here. But I'd bet a nickel it would show a normal value. CPS is a somewhat more likely suspect, since it's out there under the hood and bolted to the block, and more subject to different behavior based on temperature.