Pontiac Problems? Ask a Mechanic for Answers ASAP
There is a tsb out on "Sharp Engine Rattle Noise At Start Up May Also Set P0011 P0014 P0016 P0017". So, to begin, do you have a scan tool or code reader?
It says to suspect the drive belt but if the belt is ok and you could tell simply by removing the belt and listen if the noise goes away, then if the noise is still present and is very short and sharp in duration (2-5 seconds). This may be an issue with the cam actuators not parking properly.
Here is a copy of that tsb,
Did that tsb pertain?