Volvo Repair: 88 740 loses power at 2500rpm, air control valve, oil trap

Question
Hi Chris
I have an 88 740 non turbo. When I accelerate it stalls then regains power, runs fine up to 2300rpms but at 2400 to 3000rpms it sputters drops rpms then regains. I replaced plugs, plug wires, in-line fuel filter, air control valve, oil trap, cleaned intake and injectors, new rotor and cap, new coil (after market). The engine has 64000k miles, the auto has 256000k on tranny & drive train. It fills like it starves for fuel under acceleration or load. Did I miss something somewhere?

Answer
possibly a plugged catalytic converter (driving the car shortly with the o2 sensor out will prove/disprove this). possibly a fuel supply, not pressure, but volume issue. might have a hole in the siphon line in the tank. possibly distributor wires (small wires not coil/plug wires) shorting out at the distributor itself.