Phox, don't know where this one fits, move it if need be.

My cruise control was always a mess. It was hard to keep it from creeping up in speed. Some talked about a flash to cure it. When I changed engines I lost the vacuum pump. Recently added an electric pump and with the new pump I realized that I had a vacuum leak. I added a vacuum tank to try to offset the leak. The cruise control was weak at best and still unsteady. I finally found the leak, it is the CAD in the front axle or the vacuum switch at the 4wd control. With this disconnected the leak is gone and the cruise control works the best it ever has since the truck was new. It still is a couple of tries to get the speed right but once there it stays there for hours.

I would have made this change long ago if I had realized that vacuum was the problem. Probably the irregular cruise controll operation is caused by the vacuum leaking so that it is not steady. But a tank will help greatly.

 

When i was changing lift pump i unkonowing unpluged a vac. hose. My cruise and 4x4 would not work. So i retraced my steps and got lucky and saw the hose i unplugged.