just bought a 1.8tdci 2003 reg focus 100ps

when i first got it , turbo pulled all the time throughout all rev ranges

now it seems to be a bit iffy, sometimes it pulls hard, sometimes it pulls ok and sometimes its quite slow

i dont think the turbo has failed, no bad smoke etc etc or weird noises

my MPG is also 33mpg, instead of the quoted 53, i know i wont get 53, but 33 is a bit too low tbh

hi mate i use to have an rs turbo that had the same problem, it turned out to be a faulty actuator! (push rod was jamming on it) caused me to have turbo boost one minute and none the next. cant say for sure that it relates to you but it might be worth looking at as this controls your boost. (not 100% on diesels as mine was petrol).