1987 300 SE Euro - 103 Engine

Wouldn’t you just love to have a few weeks with no car issues whatsoever…?.

That said, I am posting again regarding an intermittent engine stumble, shudder (or big hiccup while starving momentarily) - at Idle – like when waiting for the light to change. This is once engine reaches temperature. Since my last post this became almost constant with car stalling very often. When mechanic strongly suggested replacing the fuel pump, I did so reluctantly but unexpectedly had a wonderful quiet car week. I thought the problem was solved. Until this afternoon when it happened again. By holding the brakes and flooring it at the same time I got through the light, yet feel quite frustrated.

No trouble starting cold or hot.
Fuel Filter and Fuel Pump – new
Cleaned Idle Control Valve. The breather hoses are good.
Spark Plugs look good,
-Checked fuel pressure relay solder points –looks good. I know this is not conclusive. So I removed it and bridged the 15/87 terminals. Everything cool. Well, only to an extent since I was not able to reproduce the problem while the FPR was removed.

These items below have been replaced within the last 30000 miles. I am not sure if any are maintenance items or not.Are they likely culpirts ?
EHA,
Distributor cap & Rotor
Plug wires
Gas Tank cap

So I am looking for direction here. William Rogers suggested looking at the Ignition Coil, but I do not know how to check it. Could it still be the FPR, or can I rule that out? Any Ideas would be most welcome.