'95 E420 stumbles, stalls and smells

[vexed]

My '95 E420 has developed a severe stumble and stalling problem. The upper harness and the idle control (non-ASR car) actuator were both replaced with newer versions. The car has about 59K miles on it, I bought it last year and at the time it had a occasional rough idle but nothing too bad.

The problem developed after I did two things; replaced the breather hose that attaches to the left cylinder head, it's part of the egr/vacuum system, the one that bends at a 90 degree angle and has a hose clip were it attaches to the head. It was seeping and was brittle and cracked.

The other event was I dressed the engine covers using No Touch which I now realize was a mistake since it has silicone. Once I realized that I removed and cleaned the MAF. Reinstalled it and got Codes 4,7, and 9 on pin 4 of the 38 pin connector, code 10 on pin 8 and code 12 on pin 17. I had earlier got code 10 on the 8 pin connector that has the built in LED which lead me to suspect the MAF. Before I cleaned the MAF did disconnect it to see if it made a difference, I did not think it did but cleaned it regardless.

Cleared the codes and no change. I get no flashes at the 8 pin. When the car is stumbling pin 4 on the 8 pin is dimly lit, and the brightness increases with engine speed.

The car starts idles about 900 rpm for a few seconds then bounces between 500-1000 rpm and stalls. I can smell fuel a pungent aroma like rich exhaust.

I have looked at the caps and rotors, no green deposits no arcing. I have new caps and rotors ready to go but I would like to be sure there is not another more obvious issue.

The codes have not returned. I suspect a fuel issue but don't have a gauge to check the regulator. As it idles it will almost stall, catch itself increase the idle and then stumble again and finally stall. I do not know the condition/age of the fuel pump/accumulator/filter. I am tempted to replace the filter to rule it out.

When the dealer replaced the throttle actuator in 2006 they also replaced the the LH module (not sure why).

I have read every E420/M119 engine thread I could find but most have codes or have not replaced the harness(es)

Any thoughts would be much appreciated.

I should add that just before this I added some Lucas UCL and thought the car was running better for a while. I am not getting any CELs