2002 audi a4 quatro turbo awd 1.8L 5spd man

Error code PO171 appeared and I am starting out with ordering an 02 sensor, fuel filter, plugs, and pcv. Car was driving ok while awaiting for parts to arrive, when I went to start the car, it took a very long time to start, and when it did, it conked out after stepping on the gas pedal. I know the problems aren’t linked, but don’t know where to start with the starting problem.