I've got a 98 Legacy 2.2 with 115k that I'm just starting to learn how to do even the basics for a tune. Basically until last week changing the oil and and wiper fluid was the extent of my shop experience.
Anyway, it seemed like my mileage had been suffering recently (down to 26-27 from close to 30) so I thought as something easy to try and they were due anyway, I would tackle spark plugs. Followed Haynes, got NGKs and thought I got it done but I definitely messed something up and now I think it's missing sometimes and at high speed is louder than normal (or maybe i'm just paranoid). So I guess I'm looking for any thoughts on what I screwed up on changing the plugs--something a beginner would mess up particularly if no one told you.
Also, assuming that the plugs weren't the problem orginally, what else would be the next easy, cheap solution to try to improve gas mileage. Fuel filter? One friend suggested using some fuel injection cleaner too before doing any actual work?
Thanks.
marshall
