I have a 1972 450sl that developed a very high idle, over 3000rpm. The car has run great till now, throttle linkage not stuck, no vacuum leaks, any ideas???

 

Have you tried eliminating all the "wire hook ups"?. At such old car there is always a bit of a risk at the mechanical rod/wire system. -Remove the air filter to have a better look. Smear in all the +5 linkages... -Without the engine running, have somebody to push/pull the throttle, and see if something "hangs" (don't worry to put some extra fuel into the engine, as the fuel are controlled electronically only!)
I "had" this car (1971, 450SL, but it burned as my garage to fire (caused by a NEW Toyota Auris).
Imported a "new" 450 1973 last Easter -And I also got a lot of knowledge about this cars).

How does you car drive like? It could be something funny about the electronic module, but I doupth it..., "It must be" something mechanic errors.

 

The air control valve is touchy, it can cause this issue or "hunting during warm up"