my nissan frontier died today?

[tfreewilliet]

i have had a check engine light on ever since i bought my 99 nissan frontier with 220,000 miles a few months ago. i hooked up a free scanner at autozone an it said i have a bad egr. but my truck has ran fine until recently. in the last month my battery has died twice so i replaced it. After replacing it my battery air bag and brake light come on and has been on ever since. I also noticed i have lost a bunch of power. today i was driving to school and all of a sudden all the lights come on the dash. my truck starts sputtering real bad like it was going to die. so i pull over and let it sit for a minute and try to crank it back up and it wouldnt crank. could this be the alternator or egr valve?