How do you know if your fuel pump is going bad?

I have a 97 Isuzu Rodeo that runs good until a few weeks ago then all the sudden it died on me in the middle of the road, but it started back up right away. Now there are days where it takes me a few minutes to get it started and other times starts right way. The other day i went to go start it and it was being stubborn then I noticed my fuel gauge drop to empty even though there was 1/2 tank of fuel in there. Once i got it started the fuel gauge went back to normal,so i don't know if its the pump an electrical issue or something else. Anything advice will help before i go to a mechanic. Thank you