I changed plugs, still misfired. I drive 2 weeks then change wres ignition coils and catalytic converte its stil misfiring. Why?

What is your question?

Why is still misfiring. Could I have fouled out plugs again?

How long has your 2002 Oldsmobile Alero had this problem?

Lady I bought from said motor was rebuilt then sar for 4 months 1/4 tank of gas not driven . She said about 20 minutes before she ran out of gas it started making this weird thing stuttering I'm assuming the start of misfiring and I've changed everything and it's still doing it