Fuel Pressure Accumulator Problem?

I've tried everyting I can think of to solve my rough idle hesitation problem on my 450Sl:fuel distributor, plugs, wires, dist. cap & rotor, fuel injector seals, cold start valve, fast idle air valve, coil, fuel filter, vaccum lines, thermovacuum valve. Hey, before long I'll have a new car at this rate. The rough idle beagn when the weather warmed up. The car starts and idles ok in P or N. in D the rpms fall to ~600 and it shakes. It also hesitates until I get it up to 35mph or so. then its runs ok. It is also gettin harder to start when warm. Is it my warm-up governor? Fuel accumulator?
Could someone help please?
Jmdunn