[spdbrake]

Have you got a OBTII code reader? (about $50 at Pep boys etc...)
If the IAC (Idle Air Control Valve) is sticking or the vac source hose has a leak you may have a 0505 code.
([ame]https://www.youtube.com/watch?v=6TZK_RqjjD8[/ame])
I'd also clean the MAF (use the right cleaner though)
([ame]https://www.youtube.com/watch?v=cBJnp8Q29JI[/ame])