ZDriver.com - I'd like to introduce my RATSUN

Hi, I just bought a 1983 Datsun 280zx, and it's relatively clean, seats have been re-upholstered, all the electronics work (aside from the clock) Engine has been rebuilt, only around 500 miles on it, it's cammed (at 260 over whatever stock is) And when she behaves, she runs like a dream, plenty of power, shifts smoothly, clutch is soft, a child could drive this car. However she is straight piped (gonna fix that soon)

http://i280.photobucket.com/albums/k...pszabq8qmy.jpg
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http://i280.photobucket.com/albums/k...ps1vop1gun.jpg
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http://i280.photobucket.com/albums/k...psfd2sgesy.jpg
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http://i280.photobucket.com/albums/k...psvypwr3fd.jpg

But as of recently, she's been bogging down, HARD, massive backfiring (usually around 2k-2500rpm SOMETIMES 1500rpm), loss of power. It only happens when she's warmed up, usually when it's hot out (i live in Texas) I think it might be one of many things.
1. Fuel system
2. cooling problem (problems only happen when warmed up)
3. The straight pipes (back pressure build up)
4. Something is tripping the ecu to trigger fuel cutoff

Now about the cooling issue, on saturday i was driving with some friends to go swimming, and not even halfway to the place we were going to the car started sputtering and backfiring, losing power BADLY, died on the feeder road before i could park her, got her started and running just long enough to park her at nearby park and ride. About 2 or so hours later, a storm hit and it was pouring, it stopped long enough to pick her up and drive her to a friend's place. She ran FINE, and for the rest of that day, she ran FINE. All through the rain, even later in the night when it stopped raining, ran fine

So this is my problem...please help my Ratsun. Thanks in advance.