hi got a problem when i start my 95 s10 2.2 stick at idle it gradually goes to a high idle and stays there. while driving its noticably higher and at the lights. could i have a throttle position sensor sticking or idle air control mod bad. i have a check engine light which i cannot scan it keeps coming up fault,i was told i have obd II BUT obdI? mid year change? it doesnt miss runs fine other wise.