The FOB for my 99 worked, then stopped, then worked, then stopped, pretty randomly. Didn't matter what batteries I had in it. After the last time I thought it was dead for good then it started working again, I went on eBay, searched on the FCC number from the back of my FOB and picked up 2 extras for 20 bucks. When they arrived I programmed them, using my original and then stored the original in a safe place so I can use it to program others if I need them in the future.
You would be wise to do the same.
Chris