cold start on 99-00 vs 01-03

[nic2fast]

It may just be me, but it seems like the 99 and 00 trucks have a harded time starting in the cold than the 01-03. Is there something different about the setups. We have an 01 and 02 and 2 99's one early and one late. both 99's have a hard time starting when its 40 and the 01 and 02 start with no problems in colder temps. something has got to be different. I even have the cross over tube on the late 99 and it got better, but still rough.