I have a '92 jimmy with a 4.3 and it smokes quite abit at startup after it cools down ether all day or over night. It only does it the first few seconds after it starts. The smoke just comes out then its fine after about 2 or 3 seconds. Is this some thing bad? Could the engine be going? It has 175,000 mi if it helps any.

I would be willing to bet your valve seals are shot...
(Which is not that bad of a job to fix)

Valve seals, just pull valve covers?

Valve seals, just pull valve covers?
Well, that will be a start ):h
The valve seals are on top of the valve stems..(you'll have to get the valve springs off to do this)
There is a tool to hold the vavles shut while doing this (using shop air) so you don't have to remove the cylinder heads.

Then after you get the tools to get to the valves you put a set of good quality umbrella seals on it WITH a set of factory o-rings and you're good to go...