Vn v8 running poor and drinking gas

[1989V8WAGON]

Hey hope someone can help me I've just pulled a mint running v8 from a VP calias and put it in my VN wagon trouble I'm having is it now runs like crap and using two litres of fuel per km. Why????

 

[Circlotron]

If it is idling fast and the electric radiator fan is always on then the computer might be running in limp home mode, so no spark advance, no power, no economy. When you say gas you mean LPG not gasoline? Dunno what NZ calls LPG.

 

[Not_An_Abba_Fan]

I had a similar issue with a car once, it was the earth for the injectors shorting out and holding them open. Check the injector loom. Make sure you have the wiring right.