engines revs up high then down constantly - 5min after starting on 2002 Acura TL

Don't drive it everyday. Recently, I stopped at a light and it just killed. It will start fine then it starts idling after 5min - real high,then low constantly.

Asked by for the 2002 Acura TL
Yes vacuum leak or possibly low coolant level are the likely issues that would cause this problem. Is the Check Engine Light on? If so codes stored in the computer of your car may indicate where the problem is.
no. check engine light is not on. Had new transmission and engine work few months ago....
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I suspect you may have a vacuum leak at the engine or a fault idle control valve. A good diagnostic test is in order.
Thanks. Had transmission/engine work done few months ago; wonder if this is warranty covered from that work?
I'm not sure what the scope of the work was that you had performed. If something was done under the hood, a hose could have accidentally been disconnected and then there you go - there could be a vacuum leak. I would return to the point of service just to recheck their work perhaps.