ok i have a 1998 dodge ram 1500 that works fine for a few days then stops running.i replaced the battery, i replaced the alternator its not the fuel pump because i check the fuel line its still getting all the fuel. the check engine light is not on. when you put the key in and go to start it the truck starts up but you have to put your foot on the gas for it to start and once you take your foot off it stalls out. what eles can it be? im so lost every person i take it to says they dont know.