Hello, 3 separate codes, 3 separate systems.
P0172 - Bank 1 oxygen sensor reading rich
P0302 - engine misfire detected cylinder 2
P0401 - EGR poor flow
With one bank of the engine having an rich fuel trim concern, it's something that must be monitored with a diagnostic tool that can look at the data stream.
With the misfire code, have you performed a base engine compression test?
Another "guess" would be having a leaking fuel injector, perhaps on cylinder 2, which would be causing the cylinder 2 misfire AND the rich code for bank 1. But you'd likely see some evidence of excessive fuel in the cylinder, in the engine oil, on the spark plug.
EGR valve could be stuck closed for the P0401. The DPFE sensor could be failed (somewhat common on Ford's of that era). The EGR passages in the engine could be clogged with carbon.
Strongly recommend having a high end diagnostic tool with data stream capabilities hooked up to perform more testing, such as relative compression, power balance, monitoring fuel trims.
