I have a 98 convertable, it is losing a charge when it is not running. I have pulled every fuse that is not essential for it to run. I m still losing power. Any ideas?  

Check the battery cables, make sure you don't have a bad cable that's shorting out someplace and causing the drain.

Doing the pull fuse method for tracking the drain down is near impossible with that car because one fuse can handle so much stuff.

I'll see if I can dig anything else up on what your problem might be.  

I also own a 1998 C-5 convertible which ate batteries.  Finally the dealer, Buzz Chew Chevrolet in Southampton, New York, traced it to the right power seat motor.  According to them I was running the power seat  back until it stopped moving because it was jamming against the rear cockpit bulkhead, and not stopping because I was releasing the control button.  As a result, according to the dealer, the ciruit was staying open and draining my battery.  You might want to give it a try by moving the passenger seat sufficiently forward for there to be enough room for you to be able to fit your hand behind the seat.  

Sounds like you have a parasidic draw.To test for this first you have to make sure you can disconect you battery without losing any codes .If you can disconect the negative side terminal and hook up an ameter in series and monitor amp draw as you pull the fuses one by one.this will only narrow down the circuit at fault. remember every car has some parasidic draw around 40-60mili amps. the same can be done with a test light whe the light is bright 12v draw when it dims to a dull orange 9v ok