Back flush your heater core. Then, run some water into it, with something like Limeaway, or CLR, and leave it sit for an hour or two. Flush with clean water in BOTH directions.
Vents being weird is either a vacuum problem, or, the control head is screwed up. As the control head is not a serviceable part, you have to replace the whole thing.
Your cruise not working may or may not be related. Vents, Cruise, and 4x4 all draw vacuum from the same spot. The bag o' snakes on the passenger side of the manifold. They use the plastic lines, which are notorious for getting brittle with age, and breaking easily. Check all vaccum lines, and see if there is a leak.
Cruise may also be a victim of its location. The battery likes to drip nasty things on it, and eat holes in it. Gotta remove the cruise module to fully inspect it.
Welcome to DF.