My wife was driving her Mom's S320 to work this morning and it started to act as if the cruise control was engaged. She described it as if someone was helping push the acclerator. When she got to a stop, it would surge up and down in idle. She turned the car off and restarted and it shot to 4000 rpms and then went back to acting normally. It drove a few miles fine, and then started doing the same thing. It is now at work, and I looked enough to see it is not a mechanical binding in the linkages.

Trying to work the cruise control had no effect (as in turning it off). What should I look at when I get it home? Is the throttle control unit going bad? Will that throw a code??

Thanks in advance!!

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‘84 300TD “Mountain Goat”
'62 300d Adenauer-350 Chevy - "Max"
'15 VW Passat TDI
'16 Dodge Ram 3500 - Cummins w/6-speed
'68 Mustang fastback
'55 T-bird
‘63 Studebaker Hawk