this morning, i was going to school, started my truck up and let it idle in neutral for about 1 minute as usual. drove for about 3 miles and then stopped at a gas station to get something to drink and some gum. when i went to leave, i started my truck, it reved up like normal, and then rmps dropped to about 300 so i gave it some gas so it wouldnt die. i had to put it in neutral and give it gas whenever i came to a stop, and then right about when i was to school it was fine. fuel pump? fuel filter?