Our Prius currently has around 177,000 something miles on it. We recently moved from UT to AZ and were driving everyday for a week straight, 770 miles one way. When we finished moving, our Prius started showing symptoms. At first it was minor engine knocking noises upon start, but the knocking became louder and started lasting longer. We also noticed that his coolant level was extremely low and required frequent top offs. We decided to drive him as infrequently as possible and to take him in once we settled and found some stable jobs. Unfortunately, we had to travel from AZ to CA for a family emergency, this is roughly a 500 mile trip. The knocking is worse and our check engine light came on. It gave us the following codes; P0300 random multiple cylinder misfires, P0301 cylinder 1 misfire detected, P0302 cylinder 2 misfire detected. We're kind of stranded here now. I'm wondering if a head gasket replacement will fix our car, or if it will at least get us back to Arizona? (500 miles) We are unable to take it in due to finances and would be doing repairs ourselves. We have family here with mechanical knowledge that would be able to help. Is a head gasket replacement just a band aid fix for a deeper problem? What should we pay extra close attention to while doing repairs? Are there any common mistakes or hiccups with these projects that would be good to know of? Any recommendations for checking him for further damage?