2002 honda civic lx automatic wont stay running

I recently replaced the transmission in my car. I put new oil pan gasket, valve cover gasket and plugs in it. Got everything back together and now it won’t stay running. It starts but will notstay running . I pulled the plugs out to find they were the wring ones that a was sold So They gave me the correct ones. Still doing the same thing. I’ve checked every connection. All are plugged in all lines are hooked up. Any suggestions?

With a Honda of that vintage, the first thing that I would suspect is the ignition switch.
Honda’s ignition switches of that era are so problematic that there was a recall relating to them.

Call a Honda dealership’s service department, give them your VIN, and ask if there are any active recalls on your car. They can determine this very quickly with their computer.

I drove it into the garage a wk ago. Could it really go bad like that?

How long after it starts does it quit?

With the weather getting warmer…I would replace the main fuel pump relay as a maintenance item. They tend to get wonky in warm weather. A fuel pump pressure check may be in order as well.