Recently have been having problems with my 2001 Kia Sportage, had the oil filter, pcu value and spark plugs changed about two weeks ago. Now whenever I press on the brakes or turn my truck on, it starts to shake and feels as if it would stall. Scanner is reading a "PO171 System too lean bank 1" What should I have my mechanic change.0? I don't want to get overcharged on something I don't need, thank you!