Car died and wont start?

I have a 90 lumina 3.1. Today making a right turn on the highway my car died. Didn't even know it until I went to make the turn and had no steering. Now it won't start. The only problems I had previously was a engine vibration when idling and a occasional sputter when driving. It would sputter and as soon as I'd take my foot off the gas it went away. Battery and alternator is ok. Spark plugs have about 10000 on them with new wires and IAC valve.any ideas?