Mercury Mystique P Codes (Powertrain)

Any One Have An Idea On What I Should Check First Before I Buy Any Parts For It. I Heard It Could Be The Fuel Pump Or The Filter Or Possible...

The Code P0171 On My Reader Says "system Too Lean Bank 1". After Failing Smog, I Realized I Would Have To Fix The Check Engine Code Instead...

Hello I Have A Mercury Mystique With 144,000 Miles . I Purchased It Used In June Of 2009 So I Don't Know What Work Has Been Done On It(if...