Hi, im new to this, and also new to Alfa's. Ive only recently bought my 1st one, a 156 2.4jtd on a T plate. Im also not a car mechanic, I work on big earth moving equipment (dozer's excavators, dump trucks etc..) Done this for a fair few years now, all our machines are turbo'd, got to be, and as i understand it, it seems fairly obvious to me if your turbo has gone!! I dont think you would need to take it to an alfa specialist to determine that! Our turbo's are twice, 3 times the size of a cars, and its simple, no up and down movement in the shaft, either end, but a little end float is allowed (side to side). So, as i see it, if the turbo has gone, a mechanic shold be able to tell!
I may well be wrong, but the shaft is sat on bearing, and if you have up and down movement, you have wear, if you have wear, your seals will not seal properly, if they dont they will fill either impeller or turbine housing with oil, creating smoke.
Does it smoke at all???
I bought my alfa 3 weeks ago with a cracked sump
i new it had it, got it off in 1.5 hours, took it down the specialist wealders, repaired, back on in 1.5 hours, fill up, run check all OK, brilliant. 3 days later, noise developed from engine bay, sounded like a grinding noise increasing and decreasing with engine speed (knew what it was straight away!
) took it for a spin, started to smoke, so went back home, took inlet pipe off, found play in shaft and oil in pipe.
took it off and just awaiting a re-con'd one now!!
Anyway, my moral of my story is that if your turbo's gone, a mechanic should easily be able to pick it up!!!
As its sluggish like you say, my theory would be, check the colour of the oil, if its blue (burnt oil), its probably the turbo, could be piston rigs (both would justify lack of power) if its black smoke (unburnt diesel), most likely to be a burst intercooler pipe. As i understand it, the EGR valve would also make black smoke, but like i say, ive only had an alfa for 3 weeks!!
There is of course another alternative, when was the last time it was serviced?? filters would cause sluggishness.
Good luck with it anyway!!