I had a similar problem which i found to be a "slight" Fiat design fault Ahem!.
I had powr loss, around 2500 - 3000 rpm, which i belive is about the time the turbo gets out of bed. This was coupled with a "vacuum cleaner" or loud sucking sound from near the passenger footwell.
I had a nose around and found the intercooler pipe was damaged beyond repair.
So i recommend you take a look at that. (Fiat wanted to charge over £70 for the pipe which is about a foot long with a bend in it) and that didn;t incldue the fitting. Jack your cars front passenger side up. and look underneath the passenger side head light. You should see a small black rubber hose going from your intercooler through a plastic protetive cover into the engine bay.
Check this for splits etc (Mine had been cut by the aforementioned "protective
" cover. Get your hands dirty by feeling all around it for any deformities / damage. If it needs replacing you'll need the new hose, 2 good size jubilee clips and additionally i would recommend taking the protective cover off and modifying it by making the hole the pipe goes through bigger to avoid a reoccurrance. (remember to smooth the edges and cover with some piping ( Some old door rubber fits nice and provides good protection)
If the £70 + VAt for the pipe is too much (Which it is!) then take your old broken pipe to a performance mod shop and swop it for some performance stuff, but make sure your get diameters, length angles right etc etc tec.
This is for the pipe to the the intercooler by the way
An easy fix, hope this helps. :yum: