Probably not a head gasket.
Google - "intake manifold leak" GM

You could try several tests.  A pressurized cylinder leak down test,  use an
air adapter in place of your spark plug - bring the cylinder to top dead
center and apply air and monitor.  Pressurize the cooling system with a
radiator hand pump, use a dye and black light or use an exhaust sniffer at
the radiator cap.  The actual tests have been covered in groups and are
available on the internet.

Happy modeming,
Bill

Though a little premature age-wise, there could be slow drip-leak at the
heater core. Does your wife ever smell coolant -- even for just a few
seconds?

Is the engine a 3.4 liter?  If so, you could have either head gaskets
leaking externally (they usually do not leak internally, but split along
the front outer edges) or you have the very common intake gasket
leak.  In both cases, depending on how many miles are on the vehicle,
you should be able to get "good will" warranty on the repair.

Ian

Jim,

Very likely the intake manifold gasket is leaking although GM should have
been putting on the improved gaskets by then. It can leak externally as well
as internally (not good). Pull the dipstick and make sure the oil does not
look like a chocolate milkshake. If it does, the oil is contaminated with
coolant and she should not drive the car until it is fixed. The external
leaks can be seen at the rear of the heads above the transmission. Saw some
little puddles there on my 2001.

GM paid half on my repair for my 2001 about a year ago, low mileage car
~42,000 at the time even though it was past warranty.

The coolant system caps on the overflow bottles are another weak point,
could just be the cap leaking. The caps tend to stick to the inside of the
bottles neck and break apart when removed for service etc.

Howard

thanks for the responses...i have got the car booked for Wednesday...so
place your bets...will post what the problem was after I get the car
back...thanks again...Jim