So as the title suggests, I have a random stalling issue. The car idles perfect, but what happens is that If I start the car up it turns on and idles fine in park ~700 - ~800 RPM, but when I put it in reverse there is that brief period where the idle adjusts and drops down to about 550 - 600 RPM, but the car dies. Also if I'm in park and the car is idling if I tap the gas pedal lightly to bring the RPM to about 1000-1250 RPM when it drops to stablize it will die sometimes, but sometimes not. Same thing happens on occasions if I'm stopped at a light, the idle will be perfect and steady at around 550 - 600 and then it will just die. Nothing happens as a warning it just seems to cut out, all dash lights come on and I end up shifting the car to neutral and restarting it. My recent repairs within the past 6 mos to a year are as follows:
New O2 sensor
New non-resistor spark plugs
New distributor cap
New wire set
New 120 amp alternator
Upgraded 2 AWG wire for aternator
New battery
Valve cover gasket
Oil filter/oil change
Timing cover gasket
Shifter bushing
Rebuilt transmission/fluid/filter/gasket included
Fuel pressure regulator
Fuel filter
Cold start valve
OVP

I have checked/cleaned IACV. Recently checked/lubed small piston on EGR as it was sticking. Attemped to richen up air/fuel mixture. Tested fuel pumps. Turned on ignition to get pressure and then opened main fuel line to distributor to check fuel deliver (wear goggles if doing this). I am at a loss . Only thing that seems to maybe help is that if I'm in park is that when I shift to reverse I immediately give it a bit of gas to keep the RPM up a bit so that when it drops down it doesn't cut out.

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1990 190E 3.0L