So I put a 100 mile round trip today on the truck (in sig) with cruise at 60 (2100 rpms). When the right lane merges with an on ramp, I move over, take off cruise and speed up to 73 (2500 rpms). All is normal and I maintain this speed for a while until I notice that the tc seems to be constantly locking and unlocking, jolting between 2500 and 2700 rpms, and continues to do so until I slow down under 70 (below 2400 rpms) Truck has 4L80E with 157,000 miles, and has never complained at all. Any input on this issue is appreciated.