2002 Chevrolet Impala

Engine Mechanical problem
2002 Chevy Impala 6 cyl Two Wheel Drive Automatic 121000 miles

My Impala has been giving me problems since the day that the warrenty ran out. Currently the biggest issue is that it does not start right away. The engine tries to start, then stalls out. I usually have to press on the gas lightly to get the engine going.
I live in Arizona, and that summer heat tends to make this happen more often, but it has come to a point that it happens almost everytime that I start my vehicle.
Could it be the battery? Fuel pump, fuel filter? Any suggestions are appreciated.
June 30, 2010.

If its cranking that should eliminate the battery and the starter
check if security light on or blinking and if so
try this crank engine and leave key in on position and watch the security light as it should blink for about 10 minutes when its on solid turn key off for 3 sec and try to start again

Jun 30, 2010.
The security light does not come on.
The service engine light came on and I had it read at an auto parts store, it pulled that the thermostat is faulty, and my car is running too cool. That light has since gone off.
I am nervous that I may flood the engine pushing the gas when trying to start it.

Jun 30, 2010.
What about a tune up if haven't had one yet should consider it and also don't over look the fuel filter
Remove and check air filter and MAF sensor

flooding it when starting and foot on gas
Actually on the new cars it works differently
if you push on gas as you starting you are allowing more air in and less fuel
PCM reads TPS volts and if its not closed it would not open the injectors to let fuel in
until it start and then injector will open allowing all the fuel needed

Jun 30, 2010.