When you say the alarm is weak what do you mean? I assume you reprogrammed the unit with the key on-off method, right? As far as I know, you should not have had to do that. I may be mistaken, but changing the batteries does not change the frequency of the transmitter, and reprogramming the car just enables the receiver to adjust to the remote. I'd try it again, unless you already have done it a few times. If you do a search on remotes or keyless entry you will find more on this subject.
There are several places that sell oem stuff and may have the remotes, start with the sponsors of this board, you'll find their banners at the tops of the pages.
Hope the Tide Rolls Over Ole Miss this weekend!

Good luck!
96 854 GLT