Yes the engine coolant is running through the throttle body to keep it warm and to prevent it from sticking open when it's freezing outside. I do not have those problems here in Taiwan and thus I remove those lines and connect them together so coolant just goes through. !! DO NOT TRY THIS IN AN AREA WITH FROST !! You won't be the first to find yourself going WOT and keeping WOT even when you jump off the throttle!!
The brake cleaner is to find WHERE it leaks. When the brake cleaner is sucked up through the leak the engine will respond with rising revs.