Don't know if this will help, but I have problems with my interior lights
too ('96 Caravan), they flash on & off sometimes, and I have other
electrical problems (rear windshield wipers that came on by themselves until
I pulled the wire, cruise-control not working, etc.); I think my problem was
caused by water draining on the wiring under the dash, let me explain:  I
live on the Oregon coast where it's very wet, and I'm surrounded by cedar
trees, and the needles clog up the drain-holes under my windshield wipers,
and the water somehow drains out under my dash, inside my van!  Finally, I
learned to pull the drain hose under the hood and clean it out (two, left &
right, next to the firewall).  This stops the leak inside, but I'm afraid
that the damage, whatever it is, has been done, there's an intermittent
short-circuit somewhere?

Just something to check,
Good luck,
Ray