need help truck wont start
 

i have a 2005 f250 4x4 crewcab with 170000 miles mostly stock except a sct tuner from innovative and egr delete. So about 10 days ago i noticed the tow/haul lite was flashing and it almost felt like the trans was goin in neutral and then i would let off the throttle and it would go back to normal then it would do it a number of times in my 20 minute drive from work to home. Then the next day i got in it to go to work alittle nervous about if it would do it again and it ran perfect, so i thought well hell maybe the cold was messing with a sensor or silonoid so the next day it was still somewhat warm outside and it did it 2x on my way home from work. Then it has ran like a champ since then, well i just now walked out to get in and go home from work and turn the key and it just sits there and cranks and cranks like its not even trying to start. Now im waiting on my wife to pick me up in the mini van lol but atleast it runs. Im just at a loss i have no idea what to even look at here because it started and ran great this mornin on my way here. It really sucks that its at my work and not my house because i cant even work on it. There wasnt any check engine lights or anything so im just really lost right now and could use some ideas of things to check because i really hate to have it towed to the dealer.