Hello! I've got an 88 420SEL with 240k miles that I am working on that is misbehaving in the running department. When it was yanked into my barn, it did not run. Previous owner had swapped so many parts it was hard telling where to start, 3 fuel distributors, a normal distributor, 3 EHA valves, 3 FPRs, 2 Kilma relays, cold start injector, Jetronic computer, aav and more parts to list roamed the trunk. With some help from here I was able to figure out the fuel feed/return lines were swapped around causing no fuel to get to the injectors. Got that fixed around and car still wouldn't start, instead flood to no end. Found the adjustable mixture allen screw and leaned that out a few turns and it fired up.

Now comes the part I can't seem to nail down. It'll idle(high), but only with the EHA unplugged, around 1500rpms. If I plug the EHA in, it floods it out and slowly stalls the engine in about 3-4 seconds. I have to take out the FPR (fuel pump replay) and crank till it comes to life and burns out the fuel leftover. Then I can put the FPR back in, unplug EHA, and it'll come to life. Another symptom it has is when I put it into any gear, it'll slowly bog and die flooded out yet again, and I have to repeat the process above. Timing chain has some stretch but not enough to cause a timing issue, I've been checking that with my light and it seems okay. Spark is sufficient as well, also did a compression testing and values were all acceptable per what I found on the forums. Wondering if there still could be something internally wrong with the Fuel distributor that is just going rich when the EHA is plugged in or not. Any thoughts are greatly appreciated