I put in a new ignition switch and now the car starts but wont stay running

Hello, too hard to tell online here -- physical testing of related components is needed to find out what is happening.

When replacing the ignition switch it has to be re-learned as it is an anti-theft device.This can be done by you.Put a battery charger on the battery, turn the key to the run position, look at the security light, when it goes out after about 10 minutes turn the key off then back to the run position, wait another 10 minutes until the light goes out, turn the key off , then back to the run position a third time, wait for the light to go out then crank and start the vehicle.HTH's