Car stays on fourth gear after a long drive

[ganyoti]

I have a 2001 Aztek, its driving well except after i have driven it on the hi-way for some time when i try to stop the motor stays racing high, i have to push hard on the breaks otherwise the car wants to bolt away. when i turn off the ignition all is well when i start it and the gears shift normally without any problems.
what could be the problem, i need help, is the transmission going or what

[maxwedge]

High idle is not the trans if I understand you correctly, either the iac is malfunctioning or the throttle linkage is binding, get it looked at asap.

[MagicRat]

Kingston Ontario?
Now the weather is getting cooler, you might be experiencing some icing around the throttle body, which allows the throttle valve to hang open a bit while the engine is still generating some manifold vacuum.

Ice forms when cool, damp air experiences an air pressure drop, such as when it passes through a partly-open throttle valve. City driving and short trips do not allow ice build-up because the throttle valve moves a lot.
Steady-speed driving (like bombing down the 401) can allow for ice build-up under the right conditions.

Try cleaning-up the throttle body. Consider replacing it if the throttle valve seems particularly loose, rough or worn.

[ganyoti]

thanks a lot guys at least now i have an idea