The 99 SID forks are adjustable in six ways. Most adjustments can be made externally, allowing you to adjust your forks up without ripping them apart. The most important thing is to make a note of the set-up you’re using, and record all changes. Never change more than one thing at a time.
Try increasing the air in the negative spring (thats the valve at the bottom of the left leg). For your weight, try 90psi in the negative chamber and leave the main chambers at 60psi. This should give you a plusher ride. Back off the compression damping as well the knob at the bottom of the right leg. Pull it out to adjust the compression damping, and turn it in single click increments.
Find a rutted piece of ground that you can ride over repeatedly to gauge the effect your adjustments are having. The compression damping affects how quickly the fork can react to being compressed if its too high, the fork wont take up small bumps. Turn yours anti-clockwise to reduce the compression damping.