I had the same failure. The diaphragm of the AI valve had three cracks in it. The symptoms where: 'chuffing' noise coming from the pipes at idle & extremely lean at 40mph/4th gear.
Problem was, I brought the bike ('03 TBA) in for it's 4K 'check-up'. I told the dealership about the problem (I had already suspected that part). When the service dept. brought the bike to me when they were done, I asked 'so, what did you do about the noise/idle problem?'. The reply was, 'bumped up the idle speed'. So, after looking at the bike and seeing oil spilled over it from the oil-change (come on, can't you at least wipe off the oil before giving a customers bike back?), I said 'thank-you very much' got on my ride, rode off and never went back.
I mustered up the 'stuff' to remove the AIS parts (had Brents kit), and lo-and-behold crackola on the diaphragm. Go figure. So, what does $90/hour at a dealership get you??? A lighter wallet, that's all.
jay
