>>He called the dealer for advice and they suggested the throttle actuator (damn it, it's an expensive part). <<

I would only like to mention to you that MB Doc asked if there were any codes in the AE/CC/ISC control module because that is where you may find a throttle code fault.
The code 35 you are addressing is from the HFM module diagnostic plug # 8.
The EA/CC is gotten from plug # 14.
More than likely, your mechanic has gone into that module also
[ prob has scanned all mods], but you may want to check that out.....
Let us know what you find.....