I spent five years working in a body shop as low man on the totem pole, so I got all the waterleaks. I also spent two years in the the mid 90's installing aftermarket sunroofs for an accessory/detail shop in Langley. A good friend of mine who has 10+ years experience in glass and sunroof installs (inc waterleaks) has a small shop a couple of streets behind the Airspeed store. I am sure between the two of us can help you with diagnosis or repair of your leakage. If you are interested let me know and hopefully we can line up our schedules.
If I recall correctly on that bodystyle of Forerunner the front of the roof has a pretty drastic curve coming down toward the windshield. As most aftermarket sunroofs are built one size fits all they usually have a very little curve running front to rear. I would have to assume that this would cause some pretty serious pressure at the front of your sunroof possibly causing your seal under the flange to fail over time. Also the sealant used on most aftermarket sunroofs was a strip caulking similar to the 3m stuff ( sometimes called dum dum). This stuff has a tendancy to dry up over time also leading to failure of your seal and leaking. The seal I am refering to is the one between the sunroof flange and the roof metal not the weatherstrip seal that seals sunroof body to the glass. It would be a good idea to check this seal as well and treat it with some Vaseline if is dryed out or deformed at all.
Good luck Jon.