Congrats. 1999 ... wow...
Anyway,
First advice - disassemble, make a good clean. If you feel comfortable with FULL disassembly, go with it. I'd also remove firing pin, clean it and clean the channel. Put one drop of oil into the channel and dry it with q-tip (do not leave oil inside the channel, firing pin should work dry).
After you reassemble it, do function check. If you are satisfied, go to the range !!!
Keep in mind you may need to replace all the springs soon (all depends how the firearm was used previously)
Good luck