MY last few tanks I've gotten 320-340 mi to the tank instead of the usual 380. Driving conditions and habits have not changed. Also noticing that the engine sounds louder when accelerating. Just changed the oil/filter and air filter. Any suggestions?

 

Be sure your air filter housing in closed. also check the exhaust under the oil pan, ther is a small section of flexpipe that can leak. Is the check engine light on?