I have a 1997 TJ that leaks occasionally under heavy rain conditions, does anyone know what this is and how I can stop it ??  

It is probably your antenna.  It sounds weird, but during a heavy rain, my antenna would vibrate so badly that the mount would leak.

I put a smaller antenna on ... no problems since.

Pete Barton

If the leak comes in at the base of the interior trim on the passenger door so that you have a small pool of water on the floor mat....I had that problem. It can usually be fixed my replacing the rubber gasket around the top of the door.  Some of these gasket have a poor fit allowing water to enter the door in heavy rainstorms.  

its a Jeep. all mine have leaked some. thats what owning a jeep is about. Maybe tell everyone a little more info about were the water is coming in at!  

if it's leaking aroud the floor vent, on the passenger side......pop the hood and remove the hose coming out of the firewall. that thing is notorious for holding junk in it. i took mine off a few months ago and haven't had any problems since.