Electrical and fuel problem

[mb1902.2]

My 560 SEL shut down yesterday on the freeway 15 minutes into my 17- minute trip. Would not re-start. Gas tank 3/4 full. First, the radio went out, then the instrument lighting started to dim, then the engine started to sputter, and finally the engine shut down over an approx. 3-mile stretch, and I had it towed the rest of the way. Today, I trickle-charged the battery for a short time, thinking it was the alternator, but I got the car started right away. Battery was not dead in other words. Thinking it was a fuel line/filter obstruction. I removed the gas cap and fuel came gushing out. I do not see a fuel leak, and the battery connections nd fuses seem fine.

After some searching on this forum, it looks like perhaps the fuel pressure regulator, or a clogged fuel filter. But how would that impact the electrical system? It's been raining crazy here the last few days - could this have caused a short? I know there's a short somewhere in the vehicle, because various instruments in the instrument cluster drop off at times, but I don't see how this could cause the fuel system?

Where should I start the diagnosis?

Ok, took it out, and it stopped again - same symptoms. This time the engine won't turn over, so I'm thinking it might be the alternator after all. Any suggestions before I start buying and replacing parts?

Thanks!