Before you spend a lot of money, check the waste gate to be sure it is fully closing. Put mouse milk on the waste gate hing so as to free the movement. If the waste gate not fully closing, power will be low thus fuel consumption on that engine will be lower than the other engine. Check for manifold leaks by hooking a blower (leaf blower will do) into the manifold system and use soap and water.
Good luck
Jerry N34EC
