92 Buick Will Only Start Every Other Day

My 92 Lesabre will start up and die a night. After that it wont start up every 2 days. had my dad look at it, nothign wrong with the fuel pump, its get tin gas fine, battery is good. it turns but it wont fire. you can hear it trying to start but doesnt. Took it to a mechanic and he said that its the ignition and the key. i guess there is a key on the chip and its not alligning with the ignition right.. .does that sound right?? what do you guys think??