Re: acceleration delay rev problem on alfa 147 jtd 16v
Definitely EGR valve, IMO. It's on top of the engine towards the rear and easy to get to.
Two vertical bolts (M8 - 13mm AF) hold it onto the bypass pipe from the exhaust and four horizontal M6 bolts (10mm AF) - 2 of which have M5 (8mm AF) extensions for a pipe clip - connect it to the manifold. A fiddly Italian electrical connector to the EGR as well. Undo all these and you have a complete, dirty, smelly EGR valve in your hand.
All accesible from the top of the engine with no drama (you'll need to take off the plastic engine cover first of course.)
Clean the EGR inside (very sooty) using brake& clutch cleaner (or petrol). Use a pair of side cutters to move the actuator rod back and forth, against a fairly strong spring, a few dozen times.
Put it all back, and it will work (for a month or two at least). At least you'll know what the fault was, for less than an hour's work. Order a new EGR valve (plus St/St gasket) , as the cleaning fix won't last for ever.
The ECU may need a reset if you have a computer display.