Fluctuating Idle

2002 Rav4 5 Speed has fluctuating idle...

Hey Scotty! I have a 2002 Rav4 5 speed manual with 176,000 miles. When driving I sometimes I put the car in neutral to coast up to a light. When coasting in neutral the engine idle continuously bounces between 750 - 1400 rpm. It idles perfectly normal when at a complete stop or at startup; this only occurs while coasting. The only way for it to idle normally when coasting is for the engine to be at operating temp. and for the car to sit at a complete stop for 15-20 sec, until it can completely idle down. From that point on the idle while coasting is great. Check engine light is on, have replaced one O2 sensor. Any suggestions...vacuum leak, dirty intake/throttle body, EGR valve, Idle air control valve? Thanks, Scotty.