Is it a pre or post 1990 model?

Early ones had the lock switch in the top of the handle, the later ones just pushed the handle in further.

It could be the rods sticking. Most likely though is that either the grease inside one of the motors is getting hard which is stopping the lock from finishing its cycle (a quick clean out and regrease should be suffice) or more likely it will be the looms where they go into the doors breaking down. MK4 Escorts used to do the same thing and the lock motors and wiring is identical.

The 2000e had the same issues and it was found that passenger rear door had latch issues, the front door had loom issues and once all that was fixed, the tailgate motor started to play up and would cause it to cycle randomly. Disconnecting the motor solved the problem.