I have two annoying problems and wonder if they are related!?

Under acceleration, at between 2200 and 3500 rpm ther is a 'screaming' from
the engine compartment.
It is nothing to do with the clutch or any belt slipping but sounds as if it
may be some sort of resonation.

Sometimes after pushing the vehicle hard for an hour or so (Its carrying a
motor caravan weighing over 3500kg), there is a sudden loss of power. The
engine doesn't stop, just looses power - I think that the turbo cuts out but
can't be certain. A red warning light comes on at the bottom left of the
instrument panel which means some problem with the management system?? (I
haven't got the manual to hand at the moment!). Stopping the engine and
restarting it cures the problem but, it often re-occurs later in the
journey.

The reason for asking if these may be related is that I have a diesel Audi
that has just had an Exhaust Gas Recirculation Valve  (EGR valve) replaced
that caused the turbo to cut out under load. In this case, it happened much
more often and also produced a howling noise, although different to that on
the Fiat.

My local Fiat garage (40 miles away!) hasn't got the height to get my
motorhome into the workshop to connect to the diagnostics and the nearest
dealer that can accomodate it is over 80 miles away so I'm hoping to narrow
down the problem before I take it in so that I don't have to return too many
times!!