I have a 68 charger. It fires right up and will stay running as long as I am still turning the key. As soon as I release the key the car dies. What could cause this? Thanks

Sounds like classic ballast resistor gone bad.

Ok. That's a cheap enough part. I will swap it out and see what happens.

yes if you have another one sub it in otherwise before purchasing one just jump across the the ballast terminal with a piece of wire & see if it will stay running. if it now stays running shut it off immediately & replace the ballast. If it still don't stay running holler back & we'll continue on

I replaced it and it still don't stay running. I have a mallory unilite distributor with an inline filter. I wonder if the filter went bad? I also fairly recently soldered some of the connections together between the distributor and resistor because the plugs seemed lose. However I ran the car several times since doing that. I jumpered around those connections just now with some of those electrical connectors that just stab into the wires but the car still did not stay running.

Maybe your ignition switch. The "run" position sounds like it is bad. Or maybe the wire or connector at the run position is having problems. When you turn the key to crank, voltage is supplied to the starter and the ingnition. When you release the key, it goes to the run position, just supplying voltage to the ignition. Good luck

If the ballast is okay, it is your switch or bulkhead connector. The Ignition 1 12V on the dark blue wire is gone. Easy to check with a meter. Ignition 2 on the brown wire is present, that is why it starts.
Craig

Check wiring at connector that ties ignition switch to dash harness. Commonly overlooked issue, along with bulkhead connector.