"DD",

The wastegate on the turbo system (dumps pressurized air above set point)
is controlled by a wierd vacuum transducer system WHICH is electrically
connected to and controlled by the EDS(Electronic Diesel System[engine
computer]
There are two vacuum elements a "Boost control valve" and a "Boost pressure
control" one of them is just forward of the coolant surge tank on the passenger
side wheel well(which is connected to the second ) on the same side of the car.

If you look at the turbo from the passenger side the device to the stern is the
EGR valve(It has it's own vacuum transducer right next to the 1st Wastegate
transducer.)Ahead of the Turbo is the wastegate.

I've just had to try and follow the vacuum lines and electrical wires/connections to try and figure the mess out.

Supposedly, the EDS only controls idle function and wastegate operation.

What you are describing sounds like an electrical connection between the
cruise control and the EDS...'Only problem is on the Schematic on the C.D.s
there is no direct electrical connection.

1.Check all your vacuum lines and connections.
2.LOOK at the linkages and ball joints of the "Doggie Bones" in the links
between the cruise actuator (motor) and the accelerator pedal and the
transmission "Bowden" cable
3.'Only other thing that jumps out at me is that the "Rack Position Sensor"
(Fuel) provides input to the EDS...could the sensor be getting better
MECHANICAL input from the "Cruise" actuator than the accelerator????????
[Which would make the linkage solution viable]