hey, I have a 94 Sol with the stock b16 and I had the same problem. My car would jump from about 900 rpm up to about 1300 whenever it was warmed up and idling. I had it at the dealer 4 times and they couldnt figure it out. I replaced the map sensor, IACV, 2 coolant sensors, and had the idle screw adjusted. Finally the dealer adjusted the idle all the way to its lowest setting which corrected the problem. The vacuum lines were checked repeatedly and no leakes could be found. I am not sure how to adjust the idle myself, but I would recommend trying this approach, its cheap and it worked for me with no ill side affects so far. Good luck!