Your lack of fuel economy would indicate the engine is in limp mode.
It will increase fuel load to stop it knocking if something goes wrong.
I'd double check your wiring as it sounds like you have a problem there.
Keep in mind the negine was probably running perfectly when the car was parted out so it isn't likely to have a problem from being installed in your car.
Almost all members who have these sorts of problems end up finding a wiring error or an unplugged sensor.
It will increase fuel load to stop it knocking if something goes wrong.
I'd double check your wiring as it sounds like you have a problem there.
Keep in mind the negine was probably running perfectly when the car was parted out so it isn't likely to have a problem from being installed in your car.
Almost all members who have these sorts of problems end up finding a wiring error or an unplugged sensor.