Had a similar issue and when I took the door panel off and checked it out, the spring for the punch button was messed up and sticking. It wasn't electrical for me. It's an easy job to pull it apart. Just make sure when you are taking off the big nut behind the handle and the little keeper pin you dont drop it inside the the door. Small fingers patience would be an advantage unlike my big stubs and short fuse!!! If you need a better explaination, drop me a PM. Before disassembling completly, once you get the door panel off I would check to make sure it's getting power to the switch. But if it works sometimes, I would guess it's not power related unless it's shorting out somewhere. Others may have a better idea but this was my fix for mine.I recently purchased a 99 GTS. The drivers exterior door release sometimes works. The interior handle / release always works? Has anyone had this problem before, and what is likely wrong? Any help would be great.