no idle, no idle Options

[Red_06_EvoRS]

Last Sunday, I left to run some errands and when I came to the first stop sign and pushed the clutch, the GSX died. I finally got it started again but had to keep my foot on the gas. I coasted to another stop sign, hit the clutch and watched the tach go straight to 0. I remembered reading about the base idle set screw (BISS) causing idle surges so I checked it out. It appears that the rubber cap is gone. I don't remember what it looked like so I can't say for sure that it suddenly disappeared Sunday but the BISS screw is currently in plain view. I backed it out a few turns so it will now idle but not like it used to. It used to idle 1000-1500 when cold and around 650 when warm. If the A/C was on it would compensate. Now I've got it idling around 1000 cold and about the same warm. I had it lower but it would barely keep running if the A/C kicked in.

Would the rubber cap being gone cause this kind of sudden problem? What else would?