The weather-stripping between your window and outer door-skin may need to be replaced on your '94-'04 Mustang at some point. Whether it is scratching your window, dried, crooked, cracked or stained, this guide will give you the confidence to replace the outer door weather stripping (aka Dew Wipes).
The process is simple, cheap and shouldn't take more than 30 minutes, but will require the following items:
A medium Phillips-head screwdriver
A drill and small drill bits
A small flat-head screwdriver
A rivet gun and rivet
A 11mm socket and wrench (not deep-socket)
new replacement weatherstripping
First, If you have the Mach 460 audio system, you'll have to remove the tweeter from the door. The cover of the speaker can easily be removed by sliding a small flat head screwdriver in between the plastic backing and fiber material face and prying it off.
The next step is to is to take out the one screw that holds it to the door, using a medium Phillips screwdriver. Once this has been removed, you can let the tweeter hang down by the wire or disconnect the wire and set it aside. It is recommended you disconnect the wire, as accidentally closing the door too far will likely break the speaker and/or damage the dashboard!
There are three 11mm nuts that attach the side view mirror to the door. Remove these screws and slide the mirror out away from the door. Moving approx. 1/2" or so is plenty, as the wire that runs the power mirror will hold it in place and from scratching the door. What you have done is made room between the door and the mirror, so there is room to slide the weatherstripping into place.
At this point, you will have to drill out the one rivet that is holding the weather stripping to the back side of the door. I used a 3/32" drill bit, but as long as the bit is slightly larger than the hole, it should work and you'll be able to remove the rivet.
The weatherstripping can now be pulled up and back, to easily slide off the door. When installing the new one, first make sure you slide the weather stripping in between the door and the window and not over top of the window. Push the weather stripping down onto the door and slide it to either front or back to align the holes for a new rivet. Push the mirror back into place and install the three 11mm nuts to secure in place. Re-install the Phillips head screw to mount the tweeter and snap the speaker cover back in place. Shut the door, verify everything lines up properly and shoot a rivet in the backside where you drilled out the original... you're done!
One additional optional step is to make sure you protect the new weatherstripping/dew wipe with a good UV protection plastic and rubber dressing. My favorite is Aerospace 303 which gives a nice long lasting matte shine and provides excellent UV protection.