Question, My 1993 190e 2.3 will not idle
 

When it gets warmed up it will not idle. It surges from about 1200 RPMs to about 2500 rpms, I cannot see anything wrong under the air cleaner except I noticed the kick down cable from the trans is not hooked up or is broken I don't know what it is supposed to look like. I also cannot find the switch to activated the trouble codes. Help Please.

Try replacing the temperature switch PN 008-542-32-17. If it is faulty it will mess with the idle air control valve and cause weird idle.

Check for vacuum leaks

Could also be the Potentiometer sensor on the side of the air flap assembly.

Mine had issues all the time, that's why its a diesel now. :D The OM601 will idle all day long without a care. :D