96 F-350 won't start unless plugged in in under 60 degrees
 

Had all the glow plugs replaced a few years back but even since the truck won't start unless its plugged in when temps drop to below 60 degrees. Only have 116K miles on it and it sits inside a warm garage all year. Had a relay replaced and that was not the solution and know the glow plugs aren't getting enough amps to warm up I have put off trying to pinpoint the fix as it does sit in the garage the majority of the time and just plug it in 20 minutes before I need it but just getting tired of that so wondering what all to check. Once it starts it runs fine and starts up fine too after its been run even if it sits outside in the cold for a few hours after running it around. Any ideas of things to check.

i would replace the glow plugs and relay again. make sure you only use motorcraft or beru glow plugs.

Did just that used Motorcraft plugs and replaced the relay and that seems to have fixed it. Thanks again