2003 Malibu stalls, starts up

Intermittently my car will stall when driving at high speeds. It usually starts back up IF I press on the accelerator and sometimes takes 3 or 4 attempts. Sometimes it will start back up immediately… but once it occurs it starts stalling more frequently. This has gone on for months. Seems to occur more frequently once the car warms up. Check engine light isnt on and there are never codes to read. I’ve replaced IAC, EGR, battery is brand new, cleaned throttle body, changed plugs,wires, coils, PVC valve… no luck. I’m thinking fuel pump or relay switch, but can’t fathom how it could go on this long without complete failure? On a side note, it was in need of a tune up and the battery was bad and the issue existed before any of these alterations. Any thoughts would be appreciated. Thank you