Lemme just say I did get it to start so that's not the issue. I'm still a diesel newb so I want to know what I did wrong. 1. It has been driven every day so far this week at least three times a day. 2. Started up and ran fine this morning but it was plugged in all night. Was about 21 degrees F this morning... 3. Usually takes one cycle to start if it's been above freezing or plugged in. Two if it's colder. Occasionally when it was REALLY cold it took three but started and grumbled a bit before settling down. 4. Gas guage was showing about 1/4 tank but probably less. I put additive in it and ND30w with every fill up. Took less than 17 gallons when I filled up after all the hoopla so I don't think it could have been bone dry...? Drove to work this morning and parked it. Sat there for around 8 hours and when I was leaving just didn't want to start. Cycle the glow plugs, turn the key...chuggachuggachuggachuggachugga etc almost but not quite. Okay, it's in the upper 20's, let's try again, she's cold. Same thing, almost catches but no cigar. Third try, catches and then stumbles...and dies. World record fourth try...same thing. FIFTH cycle...same thing. Now slightly worried as my DD is down with a bad alternator and Big Ugly is suddenly my DD again I grabbed an extension cord and plugged it in for about 15 minutes. Cycled it again and kept my foot firmly on the floor...chuggachuggachuggachuggaVROOOOOOM....and I'm billowing out big clouds of smoke and it idles happily (for a 6.2L at least) at high idle for a few minutes before dropping down to the low idle. I drove it down to the gas station and filled it and no issues after that. Too cold? Crap in the tank? Flooded it somehow? Driver stupidity?