Random engine misfire, think it's ignition control module and coil, COOLANT? on 2005 Saturn Ion

I'm about to replace the ignition control module and coil for the second time. It had this problem about 100,000 miles ago. This time however, the digital display for odometer will read ' COOLANT'. The reservoir is full, and the engine temp gauge never even gets up to half. ???

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1 answer
scan test for codes and do a compression test also check fuel pressure