2002 Ford Expedition Intermitent starting issues

My wife's truck has been having intermitent starting issues it started maybe 2 months ago the vehicle was working fine it started all morning every time we stopped somewhere but the last stop we made for the day when we got back in the truck and tried to start it it never started. I cranks strong but never wants to start so we were down the block from autozone and I figured let me get a fuel filter so we went it took us about 30 to 45 mins to get back. Well before I changed the filter I tried it again and it started right up. Since then it has been around 3 weeks with no problems and has now started up again I have now changed the fuel filter and I hear the fuel pump turn on but when it happened yesterday and it wouldnt start she called me to meet her and when I got there she had been trying to turn it on and again it cranked strong and you would sometimes hear it want to start but just never could I again listened to the fuel pump and didn't hear it when she turned the key so i'm guessing the line was already fully pressurized since she had been trying to start it and it never did and thats why the fuel pump wasnt kicking on. Well after towing it back to the house which took like 30mins. When we got it to the house she tried it again and it turned right on. I'm going crazy trying to figure out what it is please help. Oh and by the way there is no check engine light coming on at all.