i've already changed the fuel filter, but if it were the 02 sensor wouldnt the check engine light come on and throw a code?? because i had thaought maybe the 02 but then figured it would throw a code...but either way is there anyway i can test it, via voltmeter or something??

 

Not necessarily. Before my 02 went out, I was getting poor fuel economy, then a few months later, the CEL came on indicating a bad 02. U can use a voltimeter to test the 02, but i'm not sure what the resistance should read. Here's a link that should help u:
http://www.crxpower.net/~silverkorn/...hop_Manual.pdf

 

On a one wire O2 sensor, you will only get a fault with zero or infinate resistance on the singal wire in my experience.