94 E320 surge

[grokicki]

First thanks for all the excellent information in this Forum!

I have a 94 E320 with surge. I have replaced the wiring harness (by dealer). The car has been sitting for two years because of this but I want to repair it now.

This weekend I changed the plugs and coil boots, cleaned the MAS, intake and throttle body and it's still surges.

Now when the surging first stated it was a hot day and the a/c stopped blowing cold at the same time the surge started. Now the a/c works fine. It surges all the time with the a/c off. Most of the time with I turn on the a/c it stops surging and idles smooth, then when I turn the a/c off again it immediately starts to surge again. Turniing on the a/c does not allways stop the surging, but truning it off (with a smooth idle) always starts the surging. Any ideas what could be causing this?