won't start, sat for less than 24 hrs.even a shot of either didn't work,any idea

thanks for reply!! in short, this 7.3 has about 45.000 miles on it, so it in pretty good shape,no cat on it,,when it is cranking over and my son gives it a small shot of eather it, really bogs down instead of picking up momentum like it should and then firing up. I don't know that much about these 7.3, but I'v heard some say "best ever" some say the oppisitts,Thanks again for the reply,If ya think of anything that might help I'm all ears! my# is623-204-0029 (randy) thanks................