Running rough when started a second time

So when I reset the computer the truck runs
perfect when I arrive at my destination and turn the
truck off finish what I'm doing and start the truck
again the check engine light comes on and the
RPMs go up and down. I have replaced the idle air
control valve and the mass airflow sensor but it
only does it when it's hot, the first startup of the
day it runs fine. This is very frustrating because
obviously it won't pass smog with something
stupid like that.