If the system is losing fuel pressure, you may have a faulty fuel accumulator.
How did you check the OVP? I do not think this is affecting start-up, but all of the OVPs I've read about here carry a 10amp fuse.
Gillybenz commented on a similar 420 situation some time ago and he indicated that the OVP was a likely candidate.
What about the ignition side of the house - coil, plugs, resistor tip portion of plug wires, dist. cap; rotor?
1991 300-SEL - Model 126
M103 - SOHC
James Madison - Oppressors can tyrannize only when they achieve a standing army, an enslaved press, and a disarmed populace.
Liberty Firearms Training - After years of trying to regulate California criminals with a never ending stream of gun control laws they have still not given up with the belief that if they make something a crime that criminals will miraculously start obeying the law.