2002 5.9 gas jerking problem????

my truck has been doing this for a while now. probably at least a year but is getting worse. when i drive it sometimes it just jerks real quick and then its fine. almost like the engine is shutting off and is turned back on but a little more violent than that. i tried turning the engine off and back on and it wasn't quite as bad as when it does it by itself. im not sure if its something in the tranny or ?? sometimes it does it a bunch of times in a row..other times it doesnt do it at all. its a 2002 1500 4x4 with almost 260,000 miles on the original engine and tranny. I love this truck. ive pulled a car trailer with it for many years and even pulled it to texas and back from fl and all up thru the mountains. always been so reliable ! i dont want another truck because of how good its been to us! even with this prob i can drive it any where! no engine codes . any ideas??