you should run by your local auto parts store or shop and ask them to scan your OBDII and see if you get any codes.
I'm thinking you might get a P0507 code for idle air control issues. The manual also mentions the EVAP Control System with high idle, but not sure.
I got this from autozone too:
Trouble Code: P0507
Idle Speed Control System Higher Than Expected
IAC valve control circuit is open (intermittent fault)
IAC valve power circuit is open (intermittent fault)
IAC valve ground circuit is open (intermittent fault)
Throttle plate is carbon fouled (it may need to be cleaned)
PCM has failed