500sel Idle Issue
 

I have a 1984 500SEL w/ 130K. When starting up it likes to idle at least a grand and sometimes 1500. When warmed up it generally stays at 1500 rpms. I have a few extra Idle control boxes i've hooked up to it without any success. I cleaned the Idle control valve with carb cleaner and wd40. Barely helped at all. Though if i disconnect the Idle control valve and reconnect it i get a really good response of under a grand to almost a perfect idle. It has new plugs, wires on it. Also sometimes on start up I have to crank it over a few extra times which I suspect that may be it needs a new fuel filter. Though it may be possible they are linked problems. Any information would be greatly appreciated. Thank you.