'90 300SL (barely) running rich

[CDTurbo001]

I've been charged with diagnosing an extreme rich condition on a '90 300SL with the M104.981 engine. What I know of its background is that it's been driven very little recently and was only started (not moved) every few months - if that. The spark plugs have been replaced, nothing else - with coaxing, it'll start but runs so rich it smokes like a sick diesel. Only idles momentarily before stalling, never runs smooth, but when you're holding idle up a bit and stab the pedal it has no trouble accelerating.

I've checked for disconnected vacuum lines, wires, etc., verified proper spark plug gap, inspected the distributor cap and rotor (not perfect but appear to be in functional condition), started it with the EHA disconnected, and checked fuel pressure at the cold-start valve fitting which is a consistent 90 PSI. A few friends that know more about this system suggest the fuel distributor is probably leaking internally from damage done by ethanol gas. What else should I inspect or check before I recommend the dist. be rebuilt?

[fredws]

Look under the air flow sensor plate and see if it's wet from fuel back under there. If it is, you know its leaking out of the fuel distributor.

[nulu]

I had a bad coil cause that , make sure spark can jump a 1/4 gap