2001 cavalier temp gaugepegs no heat

[barteldt]

my always reliable 2001 cavalier is messed up when i start it it runs for about 10 minutes and then when it starts to warm up the gauge keeps going and eventually pegs out. after just a few seconds of being pegged the gauge shuts off and the no trac lite comes on too. i do have a check engine light on but the engine doesnt seem like its overheating. upper hose is soft and the lower one is firm. i get sparatic burst of heat but pretty much heater blows cold air. could it be thermostat or system plugged up head gasket etc. the gauge thing is what stumps me..