Toyota Repair: EGR vacuum Valve

Question
While diagnosing the P0446  2001 corolla problem following your suggestions.  Having a little rough idling (Vibration) and surge at starting.  Vacuum Leak?   the EGR vacuum valve(airbox) has a distinct ticking sound after warming. Have read that EGR can have vacuum leak. Is this normal? After about 120, 000 miles should this be replaced.

Answer
In 1998 with the introduction of the 1ZZ-FE engine Toyota eliminated the EGR system and used VVTi (variable valve timing) to reduce NOx emissions, I assume this valve you are referring to is the evap system purge valve, it is normal for it to click rapidly, it is a duty cycle valve and the operation is controlled by the computer as needed.
To check for an intake leak spray some brake cleaner around the suspected areas like the intake manifold etc, if the engine starts to run smooth then this is where the leak is located, to eliminate the VSV as the cause pinch the vacuum hose going to it off, this is the hose coming from the intake manifold to the valve.