My 91 f150 has always had a thing where it needed to be started twice and then it's fine ... now it's 4 or 5 times sometimes especially if it's been sitting all day slightly downhill. It seems to me that the fuel pump whine when I turn the key on is quieter than it used to be also. Any ideas?

 

my 1990 f150 4.9 acted the same way as yours,turned out to be the tank switch on the dash. it finally got to the point where it wouldn't start one day,I pulled the plug off the switch and jumped the plug with a wire and it started right up,put in a new switch and had no problems since. good luck.