IDLE CONTROL SENSOR? on 2000 Infiniti I30

idles rough when first start and sometimes dies. Car revs up when let off the gas, such as turning corners or coasting at low speed - RPM jumps up and feels like the gear is in neutral then goes back to normal. Check engine light code came up as idle control sensor, but when mechanic put it on the diagnostic machine, it indidicate everything is ok. its obvious its not.

Asked by for the 2000 Infiniti I30
When the mechanic used a scanner to retrieve codes did he experience the problem you describe. The idle air control motor is just beneath the throttle housing and is controlled by the fuel injection computer. You need to get someone to drive the car with you so you can demonstrate the problem.
Things that can cause a rough idle and stalling can be vacuum leaks, if the mechanic looked at freeze frame information in the scantool valuable diagnostic information is there. A vacuum leak may be seen in long and short term fuel trim figures. Ignition failure or vacuum leaks are the most common failure but the mechanic should have interpreted this from freeze frame information when using the scantool.
this car is currently at the shop. mechanic has checked for vaccume leaks. him and I are both puzzled with the diagnostic tool coming up A-ok.
My QX4 2000 drove perfectly until after 3 hours on the road of a 5 hour roadtrip. Scared to return now. The Speedometer, (1-6) while traveling 70 mph would jump up to 4, the engine would rev, (but no change in car speed) and stay for several seconds, then drop back down to 2. Very erratic. This continued for two hours until my destination. The car rode slightly rough after start the next day, and has rode perfectly since. Short distance driving. Not sure if the cruise control may have effected it. The cruise control was turned off after 3 hours on roadtrip. Not sure if it's a sensor. there is no engine light on.