My 2001 ford taurus acts like it wants to stall when in park?

Also it idles very low like and hesitates. The rpm gage fluctuates up and down fast.in real hot weather it starts but dies in park but will start back up in about 10 minutes.

First thing to try is cleaning both the IAC and the throttle body. My bet is neither has been done for a long time and the car is 13 years old. An $8 spray can of carb cleaner might be all that's needed plus a few minutes labor to remove the IAC to clean it then use the spray to flush out the TB.

Wipe the throttle bore and plate with a clean cloth, make sure to open the throttle and get both sides and the bore around the plate, reassemble. Disconnect the battery cable for 5 minutes. Reconnect and drive it for 20 minutes to relearn idle speed. Pat yourself on the back! Your problem is now gone!