S-10 fuel problem

I just bought a 99 S-10, 4x4, 60k, auto, 4.3, extended cab... beautiful truck. Anyway, that was about a month ago. For about 2 weeks now, it's been having the oddest fuel problem I've heard of.
For the most part, the truck typically runs fine. But for apparently no reason, the fuel pump will sorta "spool up", get loud (I know they're usually loud, but it suddenly get REALLY loud), and the truck will idle rough and die if I don't keep on the throttle. But it will start right back up like nothing. The only thing that fits in to make any sense is that it seems to happen more often when the tank is below 1/2. Also, when the fuel pump does its loud spooling up thing, I notice that my guages, specifically the tach and speedometer, dont read correctly and jump up/down quickly instead of gently like normal. Myself, my buddies, and the local mechanics are all stumped. So I'll list the possibilities I've come up with. 1) Fuel pump - But if the pump is bad, why would the truck start right up again? Sending unit? 2) Fuel filter - Changed it, didn't help 3) Water in fuel - Maybe... I ran dry gas through it already, seemed to help for just that tank, maybe I should run more? 4) Electrical - Unfortunately, sounds like the most probable thing at this point. It has a ram air hood... is it possible that water got where it shouldn't have and screwed up the electrical system? I did notice that my drivers side carpet always has a little water pooled on it and I havent found the source.
I'm new to the S-10, so I'd appreciate any help I can get with it. Thanks \
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my guess is the reason it was sold is this problem. My 96 has a intermit will not start problem been fighting for two years. Turns over, smell of gas but wont fire. Been in shop three times and they dont know what to do because it does not happen at the shop.
gone are the points, plugs, and condenser days...
good luck

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