If it is 70 out you shouldn't need glow plugs it will just crank a bit longer. It sounds like a fuel problem, maybe their is an air leak somewhere?

A diesel should fire right off unless their is something not right. I remember last winter my car would catch faster on those 30 degree days then my dads newer F150.

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2016 Corvette Stingray 2LT
1969 280SE
2023 Ram 1500
2007 Tiara 3200