RepairPal Certified shops can diagnose and repair your 1997 Ford Thunderbird. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
po401? most common problem= faulty dpfe sensor and clogged egr ports. po171,po174= collapsed/split pcv tube at rear of throttle body. not saying this is what your problem is,but I have made a very good living replacing these parts with no comebacks.
Maybe they think you charged them to much! ..just playing!..