I have a 2003 Honda Accord EX V6 with 80,000 miles. I have noticed that the car has been accelerating a little sluggishly lately. Along with that, my fuel economy has dropped off from 25 mpg to 22 mpg consistently. I recently got an oil change and a new air filter, and my fuel economy went back up to 25 mpg for two tanks worth but now the sluggish and poor mileage has returned. Tire pressure is at optimal level. Any ideas what could be going on?

 

try checking your sparks and maybe replacing them

 

fuel injectors may also be dirty, timing and valve adjustments may need attention

 

Make sure you are using the correct octane rating at the pump which your owner's manual advises you use. A basic tune-up couldn't hurt and is easy to do yourself: $10 distributor cap and rotor, plus new spark plugs if needed and a new $15 fuel filter. Also important for good mpg is a clean air filter, which you said you had replaced and the mpg went up for a while. That may be a clue? So first off, I'd check the air filter again, maybe it got clogged up again (doubtful so soon but who knows) or you may have an air intake clog somewhere else in the system. Basically, do the cheapest measures first (like a do it yourself tune-up) and use the correct octane fuel.