not usually. a dirty throttle body generally causes the engine to stall when you snap the throttle closed, or poor off idle throttle response. The high idle could be an improperly set idle or leaking hose or bad/sticking aic motor.

the leak onto the exhaust pipe could also be a failing cam cover gasket. Lots of people normally replace the cam and front main seal whenever the timing belt is replaced; shouldn't cost much more than the cost of the part itself since the seals are right there although the cam gear has to be removed and this isn't a normal part of timing belt replacement. Same with intermediate (oilpump) shaft gear.