Land Rover Repair: 01 Disco Cruise, t4 system, mechanical issues

Question
I have an 01 Discovery and at highway speeds the cruise is not holding.  It tends to slow down a bit and then speed up, but never will it stay at the speed I set.

Answer
You can check the vacuum connections to see if any are loose or dry rotted.  Beyond thet . . .The older Rovers tend to fail because of simple mechanical issues.  Newer Discos don't usually have problems like yours.  The only test system for cruise (as far as I  know) is in the T4 system used by dealers and a few independents.