I hope someone can give me an idea whats wrong with my car. I have an 02 Ford Focus zx3, for a little while my car has been jerking back and forth while I'm driving down the road but only on occasion and just for a second or two. But now it has started to idle high even after its warmed up. Its been idling between 1200 and 2100 RPM's. It also has started to stall when I stop at a stop sign or light and the battery light came on a few days ago but it goes out if the RPMs are above 2000. The battery is less than 6 months old and so is the alternator but I went ahead and did a load test on the battery. The battery tested good. I checked the alternator with a voltmeter at the battery, its charging around 15v. I have checked for any loose or cracked vacuum hoses with no luck. The check engine light has not come on so I don't have any codes to point me in the right direction. Thanks for any constructive input.
check the operation of the idle air control valve if there are no vacuum leaks. It may be stuck open.
there is a factory TSB for alt light flicker and high idle cold, idle flare up between shifts, tsb# -3-19-11, date of issue 9-29-2003 for ford focus 2002, 2003 updated reflash programming. you may want to see if your vehicle falls under this tsb