Help! I don’t Get It!, Idle went out the window... Options

[MikeInMunich]

Everything was fine, until the last time I took my 1973 2.0 D-jettronic out...

First, Idle at 1600 when warm...thought the AAR valve was stuck open.

Turned off car. When I statierten it again the idle was perfect at 800, until I touched the gas pedal. Then it was almost 3000 and wouldn’t go back down unless I turned the car off. When doing so, same thing. Perfect idle until touching the gas pedal again.

Then it got worse. Went up to 4000, and eventually, worse, in that it was right there at 4000 again even if I turned the engine off and back on. Then it seemed to be only if the car was in neutral and not under load, but that was inconsistent.

So I reckoned it was a vacuum leak but couldn’t see any tubes with issues. Then I was thinking that the clutch cable an accelerator cable were conflicting, but that’s not been a problem before for me and it would explain how the engine would idle at 800 again by turning off the engine and then starting the car again.

So, what do ya reckon the issue is?

Thanks for your help!

Mike in Munich