Coolant in the throttle body

I added a Full-Blown Stage 1 turbo to my 2014 Premium MT ~2 years ago. Last summer, I started getting idle issues and the shop recommended I check the throttle body. The symptoms were exactly what I read on the web. Finally got around to it and when I pulled the intake off the throttle body, I saw what appeared to be dried coolant on the inside of the throttle body and inside the intake hose. I had been "losing" coolant very slowly since the install (maybe a quart every other month), but no white smoke, no odor... Bad intake gaskets? Leak within the turbo? Runs great other than when idling at a stoplight.