Well, first I would suggest seeing if there are any codes in CC/ISC (I am presuming that you don't have EA) (electronic accelerator, cruise control, idle speed control).
With a scanner I would like to see how far the throttle is opening and I sure would be sure of those linkages. The throttle assy goes to a fixed openning under some "limp home" conditions (limp home is a term for the default "basic" condition the system is designed to use when it can't trust itself).
I am pretty sure that the codes can be gotten by the impulse method, seems like pin 14 but thats from memory, definitely verify.
Bosch Master, ASE Master, L1
33 years MB technician