I'm having multiple cylinder misfire in my 96 pontiac grand am 2.4?

[inuyasha_girl304]

I was going home from work and my 96 pontiac grand am 2.4L 4 cylinder started idling really rough, so I pulled over and parked and it died. Now, I can only keep it running for a matter of minutes, and as soon as i put it in gear it tries to die. I know I need a new battery, but the people at auto zone said that wouldnt cause it. They said I have a multiply cylinder misfire. My car is also backfiring, and it has never done that before. Can someone please help...

 

[motorhead'n'black]

Clean\replace plugs and wires...
Fuel injection\carb cleaner...
Both availible at auto zone.