fuel problem

Lately my car has had a fuel delivery problem. Its fine for about the first 10 minutes. Runs through the gears just fine shifting at 6500. By 15 minutes or so at about 5000 it falls on its face and then recovers in a couple seconds. I figure this is when the fuel bowls empty and not refilling fast enough. So i checked my gauge after the engine was good and hot. Pressure was between 1 and 3 lbs. When its cold pressure is about 7.5 to 8. Pump is carter mech. strip pump which kept up just fine with dual quads on my t-ram. Now holley 750. for last 2 years. Never had this problem before.