how do i know if my fuel pump is bad or going bad

I "tee in" a fuel pressure gauge and tape it to the windscreen of the car so I can read the pressure as the car starts to run poorly. Check pressure and volume delivery it should have a delivery of 1 pint in 15 seconds , 30 to 45 psi pressure running.

you should be able to here the fuel pump kick on outside of the car,ford fuel pumps are very noisy when they work