91 Ultra leak

I have what I assume is a sunroof leak - water drips down from all sides of the headliner. It sucks. Is this a common problem? How shoud I go about fixing it?

It sounds like your drain lines are stopped up! You can find the lines located under the rear doors. They go from the roof down through the roof panel and rear door frame. Use compressed air to blow them out. Be careful and use only enough pressure to free the blockage. If you use too much air pressure, you could rupture the hose. Also, check the seal around the moon roof for proper fit and general condition.