Open the hood and look for wet spots from diesel. Definitely check the injector return lines going from one to the next. I put new lines on and am still having trouble with them leaking. Have also heard the plug on the rear injector return sometimes rots out and leaks too. They just push on. After the car has sat for a while, look on the ground for any wet spots to narrow down the location. Also, check to make sure the fuel gauge sender in the top of the tank is not leaking fuel when it splashes around. You can remove the first aid kit box to check it.

The filler neck on my tank is also bent to one side. Just assumed it has been that way since new.