Help x5 2005 power loss every day ?

hi i have a x5 3.0d year 2005 42000 miels it has had its first interim service and since then we have had a progresive problem which has got worse and that is , the car will start fine every mornig but will be absoulte flat on power you can floor it and it just does not pick up 2 miels later its fine ? may i add no faults on the dash
it has been into h/c bmw and had the codes read they said it was coming up on low boost presssure they had the car 2 days and said they had changed the turo seal and unblocked the pipes ect ,
picked up the car all was fine until the next morning done the exact same fault they now say it could be air mass meter or turbo ?? when will this end
now im not silly sureley a turbo will work or not work ??
any help would be appreciated
regards andy

hi gave the car a decent run over the weekend and was fine , has started fine the last three mornings
had the codes read again today to check and its now saying air mass , boost pressure and edg ~???
dealer thinks the car is getting to much boost pressure for what is req ?
any suggestions would be greatful,as they are now saying it could be turbo @£1300.00

l going to try it for a week see what happens

I would take your X5 to a turbo specialist. It could be the turbo boost pressure needs adjustment. The mechanical linkage arm on the turbo can stretch and this causes the waste gate to become floppy and open at very low pressure causing a loss in power.

thanks for the reply when i say loss of power i mean the car goes in to lymp mode and has not done this for 6 days now? could it be air mass meter or edg ?
the dealer said it comes up boost pressure ie it is producing more boost than req hence throwing a fault ie car req 1000 and boost 1100
could this be down to the air mass meter

any help would be appreciated

up again
car has still not gone into lmp mode since its long run now 11 days i did have a tinca under the bonnet didnt realy now what i was looking at but found the air mass meter as one said it could be this that was causing the problem , i telephoned the dealer today to let him now car was fine he said it may have just been choked up ? as it does only get used on short runs ,
anyone else had these sort of problems x5 3.0 d sport 2005
regards mick

HELP
car has been fine for two weeks but thismorning it went into lymp mode on first start then for about a mile then all ok can anyone help