hey guys I own a 2003 focus zts its got 194k on it and its an automatic. When I was driving earlier today going about 35-40 mph the light up ahead turned red so I put it in neutral and coasted to the stop light and the rpm's went up around 500 or so and hung for a little while until I got to the light. Then when i got to the light it feels like it wants to shut off, the rpm's will idle at about 800 then drop a little and feel like it wants to shut off then jumps back up to about 800 and the cycle repeats until the light turns green and I head off. Does anybody have any ideas what it could be? MAF, Idle air control, throttle position sensor?