W210 e300d stalling

[cropduster]

New to me 1997 E300d that quite frankly makes me wish I would have never sold my w124. Here's the issues:

Stalls randomly, usually coming off the freeway, but now sometimes if I'm sitting at a light. Supposedly the K40 was replaced a while back, I've changed the crank sensor. Getting "Check Engine Electronics" message, generic codes of P0200 and P0400. Local Benz shop said no issues with fuel lines of bubbles. I've cleaned the plug to the shutoff valve. Checked K4o and cleaned some corrosion. Re did some solder just for the heck of it. The stall sometimes is when I'm on the freeway, it just dies and give the ETS error, then I have to pull over and put in park. Usually restarts immediately, then I can drive off and it'll either be fine or do it again. Had it do it 3 times in a 10 miles stretch, once at about 30mph, the second time at a stop, and the third at 60 mph. When I was stopped the rpms picked up, then it stalled out. This is seriously a very irritating, maddening problem, and quite frankly, I'm regretting my purchase.

Is it the K40 I've read about? I'd hate to drop $140 for it and then it not be the issue. As it stands, the car is unreliable. When I first got it a week ago, it was fine for a couple days. With each passing day of use, the frequency of stalls has increased.