2002 Mazda Millenia Mazda Millenia s surge and hesitation w

Actually, if it is worse after sitting for several days, I would lean toward an electrical / ignition problem. WHen was the vehicle last tuned up (including ignition wires)?

I have seen problems with the rubber boot that goes over the spark plug from the coil pack. They have gotten weak and have actually allowed spark to short out on the valve cover. (Actually arc through the boot)

You may want to check them. When this happens, there is usually a small gray spot on the boot where it arcs through.

As far as the fuel pump, you could check pressure after it sits for a few days. Here is the how to for checking:

https://www.2carpros.com/how_to/how_to_check_fuel_pressure.htm

If you need the gauge, many parts stores will lend or rent it.