Windshield leaking

I feel your pain. Went thru the same thing a couple years ago when I replaced the windshield in my 67 Dart. Dunno if we had a bad batch of butyl, but it didn't seem to stay in place..would kind of ooze out and didn't seal well. Finally after the unpteenth time of removing it we used silicone between the rubber and body and took care of it
My car's a 2 door post which means I had to use a 68-up gasket...that may have been part of the problem, it seemed to fit rather loosely.
YMMV