Have a 2001 Nissan Altima. Can this be timing chain or distributor cap?

First my Serpentine belt went on my car. Then new battery,alternator and fuel filter. Then my car would miss, stall, or have no power. If we turned on heater or defrost I would lose everything. But, very odd airconditioing didnot....We drove it around in town to get places, sometimes it would go and then it would lose power and couldn't get it to do anything. Now it will start stay on for a minute and then won't restart. Any ideas....Praying it isn't the chain and if it is, hoping I didn't do any damamge. Tired of putting money into car I still can't drive!!!! Please help!!!!