Has anyone had problem with there truck not wanting to idle only on cold starts, as in when the temp. falls below 35 degrees. Once the engine has generated enough heat it is fine and idles good and is good for the rest of the day. But come next morning after it has sat all night it does the same thing. When the avg. temp is higher like in the summer time there is no problem at all. I have an 01 Z71 with the 5.3L. Where should I look to fix this issue?

Take it to a shop and have the coolant temp sensor checked, if it is not reading the correct temp the it will cause this problem. If the cts tells the computer that it is warmer than it is it will not go in to the cold start mode.

not enough fuel for those morning starts. Sounds like the fuel regulator. That is a common problem on these trucks.

You may want to use thiner oil.. When your engine is cold that oil is much like sludge as is harder to move around and can cause rough idling. use 5w30 if you are not already.

Thanks, I will try these things and see if it helps. I took it to the shop last winter and they couldn't get it to rough idle. So to them it looked good, and without it throwing a code they didn't really know where to look other than to check for vacuum leaks which they found none. I will give these a try. Thanks.

well i got the problem fixed, it was the plenum gasket (intake manifold gasket) another common problem with GM. thanks for the input.