Ya you are very very right subaru kept changing how they did their air sensors on the RS
the 1999 (only) got an
Air Flow Meter And a MAF sensor according to Suba Performance in Denver (also looking at what air metering parts are available for what years)
and Ryan @ suba performance has seen a lot of cars come with with drive-ability issues when the AFM sensor goes out. he "highly" recommended i not use that sensor in my rally car. He suggested updating to an 00/01 which he said "went back to a MAP" or "went to a MAP"
my original plan was to use my 99 ecu and find a 99 harness, but after hearing about this i decided to "udpate" to an 01 harness and MAP sensor as update/backdates are free in my rally class as long as the parts are from the same body style.
So ya i believe my motor has both, i haven't actually seen my motor
bought it shipped to my crew chiefs for $475 (came fully dressed, and with a free sub frame, and borla headers) then it went straight to AIMS for a rebuild.
funny side story the seller made it sound like the motor was pretty bad, AIMS said it was beautiful and still had some factory cross hatching left on the cylinder walls. it did have some minor damage to the timing cover and a bit of time cover plastic was going around with the belt (the horrible noises the seller told me about)
so now i have a "brand new" 1999 motor with Delta cams (stage 1) Woot!