2000 Chevy S-10 FUEL PROBLEM

I have a 2000 S-10 ZR2 4.3 V6 auto, my problem is it seems to be running out of fuel at about 3000rpm under load and around 3800 in neutral. So far I have changed the following, distributor (complete), wires plugs, crank sensor, fuel filter, fuel pressure regulator(a real pain to get to) fuel pressure was checked at garage and found to be 58lbs (with engine off), the original code was crank sensor, now I just get a random misfire code. This has been going on for six months, runs fine below 3000rpm. Thanks in advance for any help, my brain and my wallet are drained.