Idle speed keeps on increasing
 

I have noticed that the idle speed keeps on increasing on my 1982 280e. Every couple of weeks I turn the idle adjustment screw another quarter turn to slow it down. That works for awhile, but then it starts going faster again. I have now run out of adjustment and am looking for better ideas. The car will get up to about 10 miles an hour without any pressure on the accelerator. Any suggestions will be greatly appreciated.

I would start looking for a vacuum leak somewhere.