I hate electerical issues! Dave by "they all flicker" do you mean all the interior courtsey lights or is it the Dash cluster lights, center display (DIC + Radio + A/C panel) also?
If it's just the courtsey lights I would say that the common ground would be the place to start. Did you have anything apart lately where you might have pinched a ground wire?
I don't know where the interior lighting is grounded but it's gotta go back to some lump o iron somewhere. This is a dumb suggestion....try checking the grounds at the back of the motor and look to see if we have any going to the frame under the car. Sorry man that's all I got without my FSM/electrical book!
Tom