i have an 85 325e and its having the SAME problems, being an ASE certified tech, i have access to some tools you dont have, such as a pair of very knowledgeable master techs familiar with early EFI and imports. we used the mitchell online program they have and found the resistance/voltage values for the AFM and found that it was working fine, but the motronic control unit (ECU) may be the culprit, there was a fairly large crack in the intake pipe but i fixed that with no results, the only things on the car that have the ability to control fuel and richen it THAT much are the AFM and coolant temp sensor, and those are only 20 bucks on ebay or at parts stores, the O2 sensor just "trims" the fuel. mine runs rich too, it seems like cylinders will shut down and after several seconds of WOT the dead ones come back online. i have also noticed that avoiding sudden throttle changes while driving can keep this from happening, if i drive down the road and close the throttle suddenly and open it back up causing it to "hiccup" then the problems will manifest themselves. plugs and wires, cap and rotor couldnt hurt, i would like to have some answers though.