I have been having a problem for a couple of years with the cruise control on our '93 JGC kicking off when going over a bump. It happens especially when you go over the start and ending of a bridge and the pavement doesn't quite match. I have tried adjusting the switch to no avail. I went to the dealer to buy a new switch, but when I tried pushing the plunger, it had the same minuscule movement of the one I have. It couldn't have been more than 1/16", but that could be off a little. It doesn't take much bouncing of the brake petal to move the switch 1/16" I have developed the habit of holding the brake petal up with my toe when approaching bad spots in the pavement. A real PITA.
Dick