I recently purchased a 02 mk4 SE 1.6 with 100k as a daily, Ive serviced the car changing air filter, cleaning air flow meter and throttle body, oil and oil filter, new coolant and checked plugs which are bosch super spark which look in good order, although i have a problem the car drives fine but on idle the engine is running rough the revs aren't hunting but the motor seems to shake as if its missing, checked for obvious vacuum leaks and still don't know what could be causing it?

Any help would be much appreciated. thanks