Why does my car go on high idle when it starts?

What is your question?

When I start the car, it goes on high idle initially. It does breaks down to normal, but after driving about 2 blocks, it returns to high idle and will remain there until the engine gets cold again.

What makes this problem better or worse?

It's worse when the engine warms up.

How long has your 2002 Lexus RX300 had this problem?

A few weeks