I dropped by "Charlie's Rod Shop" here in town today to see his newest addition, a 2007 911-2, which he bought last Winter while at his Winter Hacienda - He's replacing an alternator before taking it out to Lime Rock this weekend.
I drove Pearl over, as Charlie had never seen her so we got talking, I popped the engine cover and he asked if I was running Webers or Dellortos on it - THAT was a surprise, but we eventually came around to how a lot of Hot Rod and Street Rodders are using multiple Webers on their V-6's and V-8's - just like us. The Webers they use are pretty much the same as what we use and they ALL have the same complaint; clogged idle jets.
Someone in the Hot Rod world looked deeply into the problem and determined that the alcohol in the newer gasoline these days absorbs water in the gas (just like a very light dose of "Dry Gas" would do) and allows it to burn. At the same time, the absorbed water, if allowed to sit for a while, like in a carburetor over night, will get deposited on metal surfaces when the alcohol evaporates. Eventually the water evaporates, too, leaving a crystalline structure from the minerals in the water as a trace element on the metal surfaces. If this happens frequently enough it can eventually build up in the idle jets and begin to clog them. When the clog gets thick enough, well......you know what happens; the old Weber Clogged Idle Jet Scenario.
They all tried Red "Sta-Bil" with varying but not-so-hot results. Then they slowly switched to Blue "Sta-Bil" with better results, but they still had quite a few people switching over and STILL getting clogged idle jets.
What everyone has now switched to, with MUCH better results, is "Star Tron Enzyme Fuel Treatment" from Star brite. Charlie tells me that it supposedly neutralizes the alcohol with an enzyme which also absorbs the water and attacks the crystalline structure to make it inert so that it doesn't leave a residue. Anyone he knows of who has switched to it (and the guy is pretty well known in the Hot Rod world all the way to the "left" coast) as had NO clogged jets over the past year or so. That and the fact that I've known Charlie since I was in grade school is enough to get me to switch from Blue Sta-Bil to Star Tron. It's available at NAPA and AutoZone (I've checked) and is probably available just about anywhere (but I still have to check the "Mart-of-Walls"