Focus Tdci Broke

always wanted a mk2 focus now i have one its broke

its 2005 1.8 tdci the problems are

start's up on a morning ok and ticks over right.

on the dash it say's engine system fault and the charge light is on but the battery is charging .

i took it down the motorway today it got to 70mph on the level but going up hill it dropped to 50mph .

seems to be holding back and not much turbo .

if i rev the car sat on the drive i can hear a sort of turbo chatter. when driving it it seems to chatter back through the filter at random times [like it boosting on and off when it wants ]

dash codes are D900 / 9318 / E510

new battery and alternater fitted and new fuel filter today

thanks for any help at all i do like the car and want to sort it out darren