Re: How odd... MAF sensor rip off?
A faulty MAF will NOT stall engine. Just disconnect it and see! The MAF only provides additional information to fine tune the ECU, its not the be all and end all of the engine running!
You have been well and truly ripped off by the garage. I would write a letter of complaint requesting a detailed explanation of the reasons why a failed MAF will cause the engine to stall at tickover and for a full refund of the charges. Check the manufacturing date stamped on the MAF. Is it new or does it curiousley match the date of your car?
What did they charge in Labour? It takes 10 mins max to change a MAF and reset the ecu, which I bet they didn't do and probably explains your flat spot. A flat spot at 4,500 rpm or a reluctance to pull/rev over this is actually typical of a failing MAF - are you actually sure they replaced it?!
Lesson number 1 - ALWAYS get an Alfa dealer to return to you the replaced parts. Mine claimed to have done a 60k service inc new plat sparkplugs. Curious misfire after 1000 miles revealed new spark plugs in front easy-to-get-to bank, old originals in difficult-to-get-to rear bank ( I checked with GKN on the production coding for date of old plugs!)