So i am a new owner to a very old range rover p38 west minister with a BMW engine, i have had a very huge problem with the power from this engine i cant go uphill, over delaying in acceleration, generally the car i very weak unless its a down hill ride then everything is colours, tried switching the transmission change the ECU nothing helped so i have a 5L engine i want to swap with any ideas on this process is it a success has anyone done it before…?