I have a dome light problem, they come on and go off properly but after the car is shut off for about 20 minutes it come on . If you open a door and close it they will go out after the delay timer shuts them off but back on after about 20 min. Any thoughts

It sound like a defective timer.

I had the exact problem with my '78. The lights would either not go off or come on at random, draining the battery. Replacing the timer cured it. Timers cost in the $40-$50 range depending on where you can find one. GM doesn't carry them anymore so you need to pick up a reproduction one from one of the resto houses. You can occasionally see a NOS GM timer on Ebay.