2000 Toyota Camry XLE 6-cylinder, 120,000 miles: P0442 Code & Engine Stalling at Highway Speeds

My 2000 Toyota Camry XLE with a 6-cylinder engine and 120,000 miles has been experiencing intermittent engine stalling since about one year ago. The issue typically occurs at highway speeds, where the vehicle momentarily cuts out—ranging from once to five times per minute—and may happen anywhere from twice a week to once a month. In previous instances, the problem occurred at low speeds and even caused the engine to stall completely, though it always restarted easily—even after multiple consecutive stalls. Last winter, I noticed rough idling during the second (warm) start, which has since recurred primarily in warmer weather. I’ve observed that the symptoms often coincide with the fuel tank being fuller than usual. The OBD2 scanner currently shows the P0442 code twice. Notably, this code appears intermittently—sometimes it's present, and other times there is no code at all. I've also seen the P0442 code without any stalling symptoms, suggesting a possible correlation with fuel system vapor pressure issues. In addition to routine maintenance, I’ve replaced three components: an oxygen sensor at 18 months, the fuel cap twice (during years 2 and 3), and the EGR valve about 18 months ago due to an EGR-related code and similar stalling behavior. Despite these efforts, the issue persists. I’m seeking advice on possible causes related to the P0442 fault code and engine cutting out, especially in relation to fuel tank or vapor system components.