So I got myself a 1992 300E 4Matic for $400. It starts extremely hard when cold and feels really weak even when warmed up. I've narrowed it down to an extreme lean condition (revs up a hell of a lot faster when I press down the airflow plate and hit the gas pedal at once. Anyways my X11 pin 2-3 reading is steady at around .9V and bumps up to about 1.1V when I give it any amount of throttle. The airflow pot reads 83mv at pins 1 and 3 even after I swapped it out with a good known unit. OVP is good. Could this be a sign of a faulty ECU? How would you guys go about continuing to diagnose this car?

The ECU rarely go bad, but the fuel pumps do. I would cover all the basics first, eg., fuel pressure and volume tests, make sure the upper and lower chamber pressures are in specifications.

Thats all good but wont the car still run poorly with a bad airflow pot?