hi all havent been on for ages as i started a new job and been working hard,anyways my prefacelift z22se has started using loads of fuel so much so im thinking or getting rid,the car takes ages to get up to temp and the heaters arent as warm as they used to be also on long journeys the emission light comes on then goes off after a couple of days of round town journeys,im thinking the emissions light is down to a faulty lambda but would it be a good idea to fit a new coolant temp sensor or a thermostat to cure the temp issues.