Check engine light; PO 420 ( O2 sensor) on for 4th time. Changed. Why?

What is your question?

O2 sensor (upstream) and cat changed; light back on after 327 miles. MPH dropped by 4 on a trip I've done many times. Car back at dealer ship again. What is wrong?

How long has your 2011 Kia Soul had this problem?

This is 4th time with same error code