1999 Jeep Cherokee Sport P0138 and P0455: Related EVAP Leak and O2 Sensor Issue?

I have a 1999 Jeep Cherokee Sport with approximately 115,000 miles. It has generally run well until recently. The check engine light came on, and after scanning at AutoZone, the diagnosis was P0138 — indicating a downstream oxygen (O2) sensor issue. I replaced the O2 sensor, and the check engine light turned off. The vehicle ran smoothly for a few days before the problem returned. Today, shortly after a cold start, the check engine light came back on. At that point, the engine began running roughly, and I noticed a raw fuel vapor smell. A second scan revealed both P0138 and P0455 — a major evaporative emissions system leak. I inspected the vehicle and found a leaking vacuum line, which I replaced. However, the engine still runs poorly. I'm wondering if these two diagnostic codes are related. Could the EVAP system leak (P045-5) be affecting the downstream O2 sensor reading (P0138)? I plan to continue checking for additional leaks tomorrow. Any insights or experiences with this combination of codes on a 1999 Jeep Cherokee Sport would be greatly appreciated.