Car starts fine, but stalls at stops and takeoffs occasionlly

I have a 92 cutlass supreme convertible with a 3.1L engine. my car starts fine everyday, but after driving with no specific time period in between the car stalls when i come to a stop or when im taking off from a stop. after this the car will not start unless i hold the gas pedal to the floor. I have to do this three times before the car actually stays running, because when i first try to resatrt it holding the pedal down the car starts but the rpms are reving at about 2.5 and if u touch the gas pedal after that the car dies out, meaning the car starts but the engine is reving high like im still pressing the gas pedal but im not, anf if i do touch the gas pedal the car will stall, after doing this thre time the car usually starts and i can drive, after this happens the car will usually drive for about an hour before doing it again, that;s if it does it again because sometime it do cut off again amd sometimes i dosen't. please help me