I have a 1990 Toronado, I am having a problem with the battery draining over night. Battery is new, Alt. tested and is good . Any ideas of what could be the problem?

 

Welcome Kim!
The battery drain could happen from a multitude of things.

Even though you have a new battery, it could be bad too - my brand new motorcycle battery did that to me. The place you got it should be able to load test it right on the car.

Two experiences I had were from the radio failing in a way that the clock would stay on, also had the trunk light tilt switch fail to where the light was always on. An easy way to check the trunk light (aside from someone being in there) Is set your digital camera to no flash and 10 second self timer. Set it inside lens up, hit the shutter, close the lid and 15 seconds later, you will have the results.
I had to do that in the fridge before so I could see the penguin...

If none of these easy steps lead to anything, then it will be time to get technical... It will involve an ammeter in series with the battery and you will pull fuses until the phantom current goes away.

 

The best, sure fire way to do it. Easier and quicker with a friend helping.