Just bought a 88 Range Rover. I seek help

[cbahre]

Purchased an 87 Range Rover Classic. I had the Rover towed in and they determined a bad fuel throttle position sensor output from the ECU after a new Air Mass Flow Sensor which I found for a couple hundred bucks. A year later I figured out I had the wrong ECU in place and replaced it with the right one that came with the vehicle. The idle is better but still occasionally all over the place. It does drive fine at slow speeds on my property but when u get on the gas hard it just doesnt do anything. Almost like it wants to stall. Does anybody think I need to replace the ECU or any other suggestions? This thing has 33k on it and it might be worth fixing. I replaced the fuel pump in the tank when I first got it after some dogs chewed the wiring up from underneath. Those wires have been fixed. Looks like the catalytic converter has been replaced too.