Are you implying some of us aren't normal?
What the Dubster said. The 7MGTE uses an optical AFM. It was somewhat unusual for it's time and remains so to this day, having been eclipsed by hot wire MAF and MAP sensors. The CRC product was designed to clean hot wire sensors even though most run a burn off/cleaning cycle after engine shutdown. Under no circumstances should it be applied to the Karman Vortex sensor used in the 7MGTE.
The problem is just what he said: Some solvents will dissolve the surface layer of the plastic parts in the AFM. It's called crazing. An example is how something like iospropo alcohol is harmless to most plastics while acetone will craze them. The same process (albeit on a deeper scale) occurs when you "glue" PVC pipe together. What's really happening is called solvent welding.
The trick to cleaning this thing is twofold: 1) Using solvent that won't craze the internal optics and 2) Vapor cleaning. There are such solvents out there but most are hard to come by in the US because their manufacture was banned by the Montreal Protocol. Remaining supplies can still be bought but they're rare and aren't cheap. Just try to find some Freon TF for example.
That said there is commonly available stuff that'll do the job. As noted certain refrigerants will work but then you have to worry about the AFM handling a boiling substance. You'd still to vapor clean and it's all a lot work to go through for a part that's readily available and likely doesn't have anything wrong with it in the first place.
Supra90 makes a good point. Most AFMs are "cleaned" for the wrong reasons. As long as they put out a good square wave at close to the right frequency they're working. I suspect many are screwed with because either the owner hasn't the expertise to check them or because the problem lies elsewhere and he's barking up the wrong tree entirely.
Besides, this AFM should never need cleaning because it lives in a pretty clean environment. Contrary to popular belief the PCV system isn't a factor. The few that do get gunked up come from being behind improperly serviced oiled filters like the K&N. Don't clean your filter too often and never over oil it. Course, if you really cared about your engine you wouldn't be using one to begin with.
