Never had any real problem with the truck and still sounds and runs great but just recently it has been idling at around 1400 rpm instead of around 800. Since I have replaced the Pcv vavle and cleaned entire intake manifold and could not find a vacuum leak or gasket leak. Thinking about cleaning out the IAC valve next, would it make any difference? And if so is there anything specific I need to know about cleaning it out other than just to take it off clean it up and put it back? Oxygen sensors were replaced recently as well as coolant temp sensor, thanks.

What year is this Nissan?
I have experienced with my 2 z-24 engines that a faulty thermostat and the "base" gasket on throttle-body equipped models can cause excessive idle speed.
Hope this helps...

Checking and cleaning the IAC Valve is what I would do first. Cleaning the IAC Valve is pretty straight forward. Disconnect the negative. Battery cable first.