Is it possible the coolant is leaking from the radiator cap? If your issues initially seemed to be fixed by the new thermostat, I would suspect your new thermostat is possibly bad; its not unusual. And maybe your coolant is coming through the cap because your t-stat is stuck closed, boiling up the small amount of coolant in the hoses/radiator. I had something very similar.
My suggestion is to replace your radiator cap and thermostat, and I suspect that will address your issues.
2001 2.5L TJ, HPD30/D44 with dual OX and 4.88, full armor, X20-8 winch, 35" STTs on 15x8 black Cragar Soft 8s, 1" BL, 1" Brown Dog MM, 4.5" suspension w/ fully adjustable control arms and tie rod upgrade, OBA