ldv convoy 2001 ?

Hi people can you help , I have a 2001 ldv convoy with a ford turbo diesel after it run for about 10 mins it would slow down to 40mph , have had it checked by my garage and they cant remove the cods there are a few , i have now put the engine in another convoy sam year with the same computer and cant get it to run have bled it to the injecter pump but still no go, have also tryed to bypass relay still no go , can i get a new computer for it if so where as i am in new zealand ?