Dwight what year is your 986? I had this exact issue which was caused by a build up of carbon on the idle control valve, which was getting, "stuck" open. It's an easy fix, just clean the valve. This only applies to non e-gas 986's (pre-2000).
It could also be the MAF, or the car 'adjusting' to the colder temperature, or something else entirely. It wouldn't hurt to disconnect the battery and let the computer reset, and see if that helps the everything recalibrate to the colder climate.
