Also, when it doesn't start, are there any symptoms? Like no fuel pump charging, fans speeding up, black rectangle on the instrument cluster with the key in the on position. In case you don't know, the shifter lockout can be bypassed by putting a pencil or thin screwdriver into the hole at the bottom on the shifter plate (below the D letter on the top shifter face). Does it have an aftermarket alarm with a kill switch? Do all the lights on the dash light up and stay lit?
-Jerry