TonyD,
I have to admit to a mistake to help you here
I have a 351 / with a 650 Holley.
I washed the rear wheel wells and fenders on my car right after I topped it off with 93 octane Amoco. Unbeknownst to me, the fuel cap was apparently not tight. After I put the car away I noticed a strong smell of gas & found the tank overflowing. Since I didn't think it was making gas, I realized I had gotten some water in the tank. I let the car sit a couple of days and pulled the fuel line off the pump. Then I ran the pump for a few seconds & got about half & half water & gas. Then I cranked it up & let it run a while, no problem. Since then, I've changed the fuel filter, and run about two tanks of gas through it and it has cleared up but, and now finally, my point; What you described is exactly what was happening to me for a short while after this fiasco. I hope this helps.