2001 Dodge WON'T STAY RUNNING WHEN I COME TO A STOP

My truck has been dying when I come to a stop or driving at slow speeds. The engine light comes ON AND SOON AFTER IT WILL JUST DIE LIKE YOU TURNED THE KEY OFF. ITS GETTING HARDER TO START EVERY TIME IT DOES IT. THE LAST TIME IT WOULDN'T START AT ALL UNTIL I PUSHED DOWN THE GAS PEDEL AND IT FIRED RIGHT UP. AFTRE IT STARTS AGIAN THE ENGINE LIGHT GOES OFF UNTIL ITS READY TO DO IT AGAIN. I HAD IT PUT ON A COMPUTER AND IT SAID IT HAD A VAC LEAK, AND I HAVE HAD THAT FOR A LONG TIME. HOPE YOU CAN HELP THANK YOU.