Ok, regarding the fast idle mechanism....Can anyone tell me what exactly makes it move to drop off the roller after a few minutes? I'm asking this because I'm curious as to whether whatever makes this happen can go bad/break down. I've had to adjust my fast idle twice in the last 6 years because it will stop dropping the roller, while Mazda is convinced it should never need adjustment.

 

The thermo-wax does... Pushes a little piston.... rotates the cam. The thermo-wax can, and does go bad.... You can test it per the FSM. You take it off and put it in boiling water.... See if it works. Check the FSM for the actual proceedure, but thats basically it.