i had that fuel problem on mine, its most likely the fuel rail or the fuel lines connecting both sides. Either way the intake manifold has to come off to repair. That could also explain your mileage concern. As for the low coolant mention it to the mechanic fixing the fuel problem and they can pressure check the coolant system for leaks. If it had its routine service at 90k the coolant should have been flushed and possibly not filled properly which is likely cause filling the coolant on these cars is different from a normal car. We have the over flow tank and the upper container with the pressure cap on it. They have to be running with the throttle cracked slightly to fill them completely.