b20v high idle and will get stuck
 

my b20v idles at 2000 during cold starts, 1000 when it fully warms up. after driving a few miles the idle will suddenly jump to 2500 or higher and will get stuck until i turn off then on the engine it will go back to 1000. This wont happen again until the next cold start. What do i have to get checked? And is it possible for my idle to get any lower? the adjustment is at its lowest already. Thanks