Hesitation on acceleration and fast idle?

I just purchased a 1990 Chevrolet 2500; the engine has a very high idle and the engine bogs down or hesitates when accelerating on takeoff and passing another vehicle. It also backfires sometimes when you snap the accelerator pedal. The previous owner tried fixing the problem. He replaced the TPS, MAF, EGR, plugs and plug wires. He also removed the catalytic converter. He also said that he checked fuel pump pressure and it read 10 psi. After I got it, I replaced the fuel filter and checked base timing (base timing was 2 BTDC). Then I cleared any codes and ran the engine until the check engine light came on. I read the codes and got code 44 and no other codes. That is all the info that I know about the truck. Any and all help would be greatly appreciated, thank you.