For cold starts, check your battery first. It could be just discharged. Also if you have too heavy of an oil it will hard start in the cold. Another thing I figured out with a honda, was the Engine Coolant Sensor was bad, causing hard starting in the mourning because it controlled the computer before the oxygen sensors were hot enough to work.

 

Well the first thing i checked was the battery and the oil is the right wait 5w30 and i replaced the engine coolante temp sensor

 

I have a 2000 jimmy with the 4.3 and i had a problem with it cranking but not starting. Chased the problem all over butfinally my mechanic told mefrom experience with theses trucks that an ignition sensor in the steering column was shot. it was a fuel cut off apearently for the security systems in these trucks. it didnt seem temp related but didnt really notice. once it was replaced i havent had a starting problem since

 

Thanks for the info 00blkjimmy if have been doing a lot of research and that ingintion switch seems to be the only thing let that i havent changed that could be the problem