Quote Originally Posted by stealthee View Post
160 thermostat is a terrible idea. Put a stock 195 in its place.
This^

If the engine is having a misfire, a code would be present, have you pulled codes? A bad head gasket doesn't mean you would loose coolant, the head gasket can break in between cylinders and loose compression that way, a compression check is a test for that. I don't think your problem is your head gasket, I'm just giving you that information. I would start by pulling codes and let the PCM tell you whats wrong and where to start troubleshooting. If there are no codes, check for vacuum leaks, and do a full tune up. Plugs, wires, fuel filter, the works.