Are you sure the throttle servo isnt getting weak after a couple minutes? Make sure it is pulling the slide(or rotary) all the way. Also, make sure the truck still rolls freely in both directions after it starts acting up. Is the slipper clutch on your transmission tight(I cant remember for sure, but I believe the 3.0 has a slipper?). You may have to keep running it and analyzing things to figure it out.