260E Cruise control speed is 5 mph greater than set
 

I replaced my 260E cruise control control module (under dash) with one from a 300E. Most of the time works great. But:

1) Jerky cruising....not real bad, but kinda jerky
2) Sometimes you need to set the speed 5 mph lower than target.

My thinking is that it's an actuator needing lubing, but I don't know. Any insights here?

One thing I noticed was that the CC controller I replaced had a snap on module to it, whereas the one I put it, doesn't.