hello,
recentely bought a 98' exlplorer sport. i live in upstae NY and its my first 4X4. drove for two weeks fine then i shut it off and i went to start it and it would crank but not turn over. i checked for spark and it had spark. full tank of gas. then a man at work said i might have lost the anti-theft code in my chip. i took it two the dealer and theysaid that it wasnt the key but that i needed new plugs so after i put in new plugs they said that the engine had no compression. i had it towed from the dealer to a garage by my house and he ran a diagnostic that said my crank shaft was disabled i then found out that i had an old car starter in and that might have been it. i took that out and it didnt work. then i took the battery out to get it out of the cold. when i brought it back two days later to put it in i started just to see and it started and ran fine. so i thought that wasit. and it ran too good for it to be compression so i thought the dealer just wanted my money.i drove it all day and it ran fine then i went out they next morning and i wouldnt start. tried 15 times over a week nothing then it started again. replaced fuel pump relay and cleaned MAF run fine then in a few days it happened. still never know when it will crank but not fire. any ideas? sorry for the length but i figured details would help. thanks -adam

 

sounds like you need a new crankshaft position sensor also clean your iac also find a new dealer