If your car starts, the VATS or PASSKEY (chipped keys) system has been bypassed. Don't waste your money on keys (FTR, I can get them for about $15 apiece at a local locksmith).
Your car randomly dying is problably corroded batter cables. Pull the boots off the cable ends at the battery and clean them VERY well. Then apply dielectric grease and reinstall them.
Your car is a potential victim of the dreaded upper intake manifold failure, as well as DEX coolant eating away at your Lower intake gaskets.
More information here:
Since you have a combination of Electrical and Mechanical questions, I'm moving your topic to 92-99 for better visibility. This section is fro Audio and Aftermarket Electronics.