Okay O2 sensor was hooked up still, I'll have to check its functionality via diagnostic port or bench testing I've seen is an option too. Not sure exactly how, but I can use the search feature for that. While i was out testing, I unplugged the EHA and the car's behavior didn't change at all when warm which I presume is to be expected? Unplugged both EHA and O2 sensor with no change in behavior.
Is there a way to take the air flow potentiometer off and clean the contacts off with a pencil eraser? I did that trick on my SL's TPS and it seemed to help (electronic djet). I have messed with adjusting the EHA before on my 126 but that was because it ran horrible when I got my hands on it. My 124 runs well in comparison to what that was like, so I am a little hesitant to adjust the EHA and cause adverse effects.