hey, i have a 98 manual se, i've never had great mileage(17 city/24 hwy), and i dont know why, i changed the fuel filter only 4k's ago and changed spark plugs to ngk's, also put in k&n drop in charger. A few months ago it wouldn't start, turns out the camshaft sensor went bad, i replaced that and it worked fine, but lately it has been struggling to start, any ideas or suggestions would be greatly appreciated.

 

check starter, alternator, whole wiring, throttle body, and battery.

 

Tire pressure and PCV valve. Maybe knock sensor is bad? Check for knock sensor ghost code.