My 2000 dodge Dakota has had the water pump replaced a seized viscous coupler replaced and a blockage that was opened up after the heater core was flushed. 600 dollars later they tell me it might be the head gasket. I have a cylinder 3 misfire and they also say plug looks good whatever that means. Can anyone come up with another issue or am I up for a new truck? There is no outside leakage and fan works fine.

 

Truck has just under 100000 miles on it