Well, no luck.
I pulled it all apart. The Idle control hose from the valve to manifold didn't have any visible flaws although it was definitely softer than the new OE Mercedes hose.
I put it all back together and it ran great the rest of the weekend. This morning the car got about half a mile until it cut out again, unplugged the EHA valve and it started up, runs poorly and it hard to get higher speeds but it runs.

Update.
I discovered the intake boot was not seated fully on the throttle body, fixed that and it ran great for about four days.
Took a smoke machine to the car, there was a severe leak on injectors #1 and #3. I replaced the injectors, seals and o-rings on the holders, cleaned the manifold and the holders , reassembled everything, now it wont run for more than 40 seconds before it stalls, either at idle or speed.
Adjusted the potentiometer slightly with no change. As usual It runs, poorly, if I unplug the EHA valve.
Tomorrow I am going to check it out with the smoke machine again and have the potentiometer adjusted properly.
If that doesnt work I am done with this car.

With the massive air leaks, your mixture will be way out of whack especially since the initial shop adjusted it when you had the vacuum leak. Start by making sure its getting 50% fluctuating from the X11 connector.

CIS-E is a royal PIA to diagnose, but don't give up yet.

Since the EHA uses the O2 sensor as the way to adjust the mixture, I am wondering if its possible that the culprit is a bad O2 sensor? They tend to get slow after ~100k. You can get a 1990 Mustang GT Bosch sensor from any local parts store for ~$35-40 and you just splice it in. (2x white heater wires DO have correct orientation to follow though FYI -- wire up, hold in palm of your hand, start car, if sensor starts getting hot, good to go plug in exhaust bung).

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I forgot to mention that I replace the O2 sensor too. We will see what the day holds....

well, so far so good. Smoked it again and everything is good and tight, readjusted the potentiometer and it has run well with no stalling. it stills has a mild rough idle sometimes but other than that is seems to be fixed... for now.
Thanks for the help.

Back to square one. Wont run with the EHA valve plugged in.

Fuel distributor?

damn...

Any chance you can do a fuel volume test? At very least you can rule out EVERYTHING backwards of the distributor and makes less of a guessing game.

Pretty easy to do as long as you can jump two pins on the fuel pump relay:
First part in this article:
http://w124-zone.com/articles.php?article_id=48

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I'll have to collect some spare lines and give that a shot.