Car Starts then immediatly stops...help

Jump a tempory wire across the ballast resistor.
If it fires and stays running you found your problem.
As soon as they heat up they can give you crap.

If it still dies, try wiggling the key I had an old dodge truck that would start the die, you had to hold the key in the right spot to keep it running.

If it is still DOA try this.
Check the bulkhead connectors where they go in to the firewall.
Common place for corrosion.

It still sounds like the ballast resistor is shot.
They are only $5.00 change it.