Is their a link to the above schematic and a parts list?

I know this thread is few years old but I have a 84 Carrera with cruise control. I have 2 modules that are doing the same exact thing.

The cruise engages perfectly but then it hunts up down within 5-10MPH.
- Say I set it for 50MPH it does so just fine.
- Then the speed starts dropping till it hits 45MPH
- Then it snaps back into acceleration
- Hits the 50MPH set point
- Repeats!

I have 2 Cruise modules they both do exactly the same thing.

I then removed the vacuum servo and bench checked it with hand vacuum pump and a 9vdc battery to activate the valve. Valve functions just fine and it does not leak vacuum.

I know it's possible both modules are failed the same exact way, but not likely.

I also removed all the varnish on the solder side of both boards and re-soldered both board still same issue.

Thoughts?