I have a similar issue. I would be able to turn the cruise control on, but it would not set, then would very soon turn off on it's own. Now, it almost is impossible to get it to turn on even, and when it does, within a second, it turns back off.
The issue started right after I had the transfer case and fuel pump replaced. They also took off the wheels to reset the bead on the tires to fix a slow leak.