tps?

[smoknblack01]

hello i have a 2000 f350 and while cruising down the road with the cruise control on going down hill the truck starts to buck. it seems like its giving it gas then lets off gives it gas lets off over and over again untill i reacg the bottom of the hill. Also at idle it seems to rev itself up every few seconds. and while idleing i try to give it just a little throttle and it jumps to 1200 rpms there is really no inbetween. could all this be related to the tps?