Chevrolet Repair: 1992 chevy K1500 350cid, air control valve, chevy k1500

Question
I have a 1992 silverodo 4x4 with a 350 when i start it up in the morning it runs like its missing on multiple cylinders but also it does this when ever it cools completely down, it will clear up if i get into the throtle and hold it, then it runs fine. it has all new sparkplugs, wires, cap, and rotor. i was thinking maybe map sensor.  
if you think you can help that would be great thankyou  

Answer
There are a couple of things this could be. Idle Air control Valve or the timing could be off. Usually this is a sign of old worn out plugs or wires but since they have been replaced it could also be a sign that the valve guides could be leaking oil into the cylinders overnight and fouling out the plugs. You see, as you start it and rev it up you are forcing air and fuel into the cylinder allowing it to clean itself out. Just an idea but wait till the engine is completely cool then pull a couple plugs, I would bet they might have some oil on them. If not then I would say your IAC valve isn't functioning properly and choking out the engine.