will be the pressure release valve they are on about common on these they also need coding by fords, deffo a injector leak of test etc if they gone they over fuel and fuck your engine, as for the diff i just rebuilt mine cost me 90 quid but pros can come to your door and do it for £600


prv is 90 quid, injectors stupidly it makes no sence to recon them just buy new ones at £150 each and they will need to be recoded also