Stock b16a2 with original transmission aem intake stock headers and a mugen twin loop exhaust. Only thing i can think of is the ECU... previous owner said it's chipped. Also I have a very light coolant leak through exhaust.. getting head gasket re done soon but the loss of coolant is so light you can hardly tell.. what should I do. This gas mileage is just ridiculous!

 

Do a compression test and/or try another ECU.