About a week ago my truck would jerk when I would try to set the cruise control now when I set my cruise it does nothing and also, my speedometer is nice and smooth up to 60 mph and then it starts to sweep back and forth from 60-70 non-stop. I went ahead and and serviced my rear diff. so that I could inspect my tone ring and it is good also, tried 3 different speed sensors and I replaced the connector for the speed sensor. I would appreciate any feed back on what else, to check. Thank you!