New ignition switch - bad already?

You probably have an issue at the lower steering column connector and or firewall connector. I use a terminal block on the steering column connector (most are melted) and make sure the firewall connector is good. Check all connections using voltage drop method while moving wires. I gave up on aftermarket switches and disassembly old OEM and clean contacts. The key mechanism can also be aligned better with shim washers. Look at the switch when you hold it in start and you'll see what I mean.