Pontiac Repair: head gasket?, intake manifold gasket, head gasket

Question
I have a 2001 grand am gt.  There are exhaust fumes in the coolant reservoir.  The car can idle rough in the morning upon starting and has thrown a P0300 (random misfire) code.  The car overheats and blows coolant out of the reservoir.  The intake manifold gasket and thermostat have been replaced?  Does this sound like a head gasket?  A compression test showed all cylinders between 160-175 psi.  Any way to be sure beyond the hydrocarbons in the coolant or is that enough?

Answer
Hi Denise:

Yes it sounds like a head gasket issue or worse a cracked head. Has the engine overheated severly? These engiens are noted for head gasket issues Usually the rear bank back by the fire wall. When it's running rough in the Am I'm sure coolant has leaked into the combustion chamber and that is causing the misfire. All signs lead to taking the engine apart for exploritory surgery to see what damage has been done or what is leaking. How did you discover the exhaust gases in the coolant? was the dy added to the coolant and it showed up that way? If that's the case then sure enough it's going to have to come apart.
Good luck :)