Question re: '90 300CE & M104 engine

[BENZ-LGB]

My 1990 300CE has just developed an "issue" (they are always "issues" and never "problems"). Before I take it to Enrique @ Mr. M.B. Motors, I would like to take a stab at fixing it myself.

Here is the "issue":

1. The car starts fine (though not always on the first crank), it runs fine, accelerates fine and it idles as smooth as butter.

2. If I stop and turn the engine off and then start again a few minutes after stopping the engine, the idle will be a little shaky (but never to the point of rough). If I try to drive the car, the throttle does not respond, I can floor the car and I don't get much movement, then the engine "catches" and the car accelarates normally.

3. If I let the car idle for 30 seconds or so, I don't get the problem.

4. Also, if the car has been stopped for more than just a few minutes, then I don't experince this issue. I have informally timed it, and if the car is stopped for more than 10 to 12 minutes, then there is no problem.

5. Only a short, brief stop causes the problem.

6. When the car experiences the "slow accelaration" issue, it feels as if the car is starved for fuel.

7. Fuel economy has remained the same (in fact, fuel economy went up slightly after putting in a new set of Michelins).

I had suspected the fuel pump(s) or the fuel distributor, but the fact that the car only does this after it has been stopped for a brief while (and does not do it after a long stop) makes me question my diagnosis.

I did a search here and did not quite find the same issue (maybe I was using the wrong search terms).

Any suggestions would be greatly appreciated. Thanks.