Jorgan - I was hoping no news was good news.. Does the computer show L/100 km? The fuel filter is actually quite easy to do since its got the quick connects and one screw. You take off the screw then use a 17mm open wrench to pry off the hoses. Put up a new filter and push the hoses back together.. You can either empty the fuel system, or spill some.. your call

alscherntz - 0171 is rich, which can be caused by high fuel pressure.. Is there an autozone around? You can get a fuel pressure gauge with their loan-a-tool program for free (you pay now, refund when you return, you can keep for 30 days if you want) and check. If you're not sure how to use it, if you go while their slow (better yet, send your daughter :-), and they'll do it for you. You want to see 43.5 psi on the gauge, higher and you've got a problem.. If you've got a pick-n-pull closer than the autozone and $10 to spare you can just switch out and see what happens... You can get an extension for the gauge and drive with it.. The range for your pump is 220-310kPa (31.9-45 psi) outside the range, you've got issues.

Another thing you will want to try is blowing into the return line. If you feel resistance there's a clog there..

I'm assuming you've pulled your plugs correct? Did any look different from the rest, or were they all the same?

I'd do those tests before i built the smoke machine. The lack of response at WOT leads me to believe its not a cracked elbow (though, i'm sure in the end, you'll try everything else and that'll be the problem...)