Bank 1 is too rich code P0172

The car drives very well but when coming to a stop the idle drops to about 500rpms and the car will die and sometimes hard to start but will start back up after you pump the gas. When you start the the car the idle is to normal. Now I have been told its the map sensor and someone told me its the o2 sensor the thing is I have played this game before and spent over $500.00 last time tring to work on a car so I could really use a experts advice