Hello guys, Just going to cut straight to it. about 2 days ago, my idle was normal no bouncing when im at a complete stop, usually only when I would start the car in the mornings, the idle would bounce from 750 to 1500 but yesterday after about 100 miles of driving, anytime I put the car in neutral it will rev with out my foot on the pedal, I took it into the shop and they said its my coolant sensor? where are these located so I can see about getting it fixed, also I think its just a vac leak but any help will do thanks.