To be the MAF at all. My car was a pig to drive for last few months. Under powered slow and no Alfa pick up. I know it's only a 1.4 but it still has the Alfa engine style to it. Ie loves to be revved and gets better to be revved.
I always thought in my mind it was a MAF 100% or a lambda sensor that has decided to take a death. But it wasn't it was the insulation in the back box that got a knock must have blocked the internals of the box and thus reducing the air flow from the exhaust.
I changed the back box for a Ragazzon and now it's back to normal. Thank god I did that before I went ordering MAF's etc.
Ah just saw your thread on it, got the same as you. Best one as it fits nicely in the gap, especially compared to the standard one! Got it from cat-back with the one silencer (don't think it needs 2 really)