Hi, I just picked up a 1986 300E, and it has a bit of a rough idle when stopped in drive (and a a intermittent idle surge 500-800 rpm).

I'm going to replace the vacuum hoses first. Dumb question, do I just go buy a bunch of vacuum hose from Pep Boys and cut to length? Or do I need to go to the dealership?

Thanks

There aren't many vacuum hoses in a 300E. MB uses hard plastic line like you might have seen in a VW. You can get white line by the foot from a BMW, MB or VW dealer. Ideally you'd keep the color coding but dealers don't normally stock the various color coded lines. You can use the more common black vacuum hose in place of the plastic line but you might need a coupling here or there.

Rough idle is not uncommon in these cars and all too often it's not caused by a vacuum leak.

Sixto
93 300SD