Clicking noise coming from engine idling and accelerating

I think you may have an exhaust manifold leak at the cylinder head. Get it checked out by a GM specialist. If you want to find a specialist, here's a directory link for you: https://repairpal.com/pontiac-repair-in-san-diego-california

If the noise is louder when cold then I would agree you might have an exhaust manifold gasket leak or possibly a cracked manifold. It would be a good idea to check the oil level, if it gets low it can cause the lifters to make noise. Either way it is best to get it checked out especially if the oil is low it would be good to determine where the oil is going.