I would agree that this is most definitely an electrical condition, with one possible exception. NOVAZ27 has good information. Alternator issues can cause this, but there's also one possibility that nobody here has brought up, and that could be a loose belt caused by a worn out belt tensioner.
Make sure your battery cables are clean at the terminals on either end.
You're wasting your money on distributors and water pumps.
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1988 9C1 - Modified LM1 @ 275HP/350TQ - TH700R4 - 3.08 8.5" Disc Rear - see it at
http://www.silicon212.org/9c1!
2005 Crown Vic P71 - former AZ DPS - 4.6 liters of pure creamy slothness!
1967 El Camino L79/M20 old school asphalt raper
Remember - a government that is strong enough to give you everything you need, is also strong enough to take everything you have.