Sounds like it is missing.

[1629dill]

It got a little cold over the weekend, low40s upper 30’s. After I started my 1999 Suburban it ran very ruff and it sounded like it was missing. Once it started to warm up the missing stopped. Just want to know if this is a sign of a problem or is this normal as the temp starts to drop.

[rameye]

Most likely some glow plugs not working...now that its cold, you are starting to notice it.

Normally it should fire right up and idle smoothly.

Mine does get a little "ruff" if its well below freezing for about 20 seconds or so.

[6.5guy]

We have a '00 and a '95 withg 6.5 turbos in them. They run rough for the first few seconds when it gets cold also. It seems like the glow plugs started to get weak on ours at around 90,000 miles. My uncle has a '93 GMC 3/4 ton diesel that had 175k miles on it when he put new glow plugs in.