smog pump noise
 

Started my 190e 2.6 this morning, ran fine, shut it off to check something under the hood, refired and the smog pump sounded like opening day of duck season, did this for about 30 seconds, then back to normal which is bearly notible. now idle hunts a little between 800-900rpm, what happened,can this be related.

that smog pump is dying,you need to find another or go with a rebuilt.one other option possible.there is a belt size for that engine without the smog pump-just use that and bypass the pump.