I'm no expert but maybe my thoughts will provoke a real expert to give you the right answer. First, I would not have thought the switch would be part of the headlight problem ; I would think headlight relay perhaps (I assume there is one - like I say I'm no expert). You can do that yourself. I bit of warning : my opinions are a bit slanted towards things I can fix! First, I wouldn't think of plugs as killing the engine, unless we were witnessing a real sad group of plugs that were limping along in a hard-to-imagine fashion. Wouldn't an intermittent bad coil create a sudden death scenario? Or for that matter just a weird loose wire to the coil. I had intermittent problem when the wire that comes out of the distributor from the sender was grounding out, after a mechanic fooled around with it. Check to see how much corrosion has eaten your wires to the coil, since that's cheap to do. I think it uses those horrible tabs that wiggle free and allow dirt and grime to get in there. Your mechanic thought fuel pump - maybe with good reason. You can get a little tube or a stethascope and hear it running or not. That's cheap. Even a Christmas paper cardboard tube would work fine. Anyway, I think the answer to this depends in part on how many components are reasonably thought to be working bacause of regular maintenance. Was the mechanic putting in plugs because the car was in bad need of them so he might as well start there? Or was it just a blunder? My guess is that it is probably not a fuel problem because the problem vanishes for a day then appears 10 times in 15 minutes. That sounds electrical to me. And despite what I said about wiring, it really sounds like an ignition component failing. Sender, coil, etc. One caveat though, if it dies with a sputter I *would* think fuel control but if dies quick as lightnning I would think ignition. If it were my car I would probably just start replacing cheap parts that were pretty old (electrical parts) until the problem went away since I would figure at the end of the process I would have nice new components.(Plugs, wires, coil, sender, cap , rotor, etc.). Then I would think about the fuel control system. But as I said, this approach is biased towards thing I am able to fix! Anyway I would be happy to hear how one of the experts here would approach it. If I had to guess one thing I would guess impulse sender.