Pontiac Repair: 1998 Pontiac Transport Temp Spike, intake manifold gasket, head gasket

Question
I have a 1998 Pontiac Transport with the 3400 SFI engine.  Shortly after driving the vehicle the temp gauge will spike almost to the red line then go down, back up and so on.  It never pegs out or get to the red in the guage however very close.  It doesn't take long to spike either.  It can spike the temp within a mile of driving it.  I was going to start replacing the basics, thermostat and water pump but then somebody mentioned it could be a head gasket.  Is there anything I can do to isolate what the problem is?

Thanks!

Answer
Hi Sean:

well it sound to me right now that It's low on coolant. That is a sight of temp spikes. But why is it low? Most likely cause is a bad lower intake manifold gasket causing the leak. If the system is not low on coolant than a thermostat could be the cause or a head gasket. There is a product you can buy at the big better parts stores that you add to the cooling system and the chemical will change color if there is exhaust gases leaking into the cooling system due to a head gasket leaking. Good luck :)