it comes off the main air filter box and connects to the 4.0l engine. tube runs behind alternator, here a picture. is that another device?

 

mastertech or anyone know what the black piece is?

 

could this be the return hose for the breather tube? anything in this plastic or is it just a 90 elbow

 

That's the return yes. The other half of the PCV system. There's nothing inside it's just hollow.

 

would you run oil cleaning products those to clean the engine in this vehicle? vehicle has 47000km. I thinking running as per instructions 5 mins at just above idle and then remove old oil and filter and put new fluid.

 

I wouldn't do it. If you haven't neglected it, you will be fine. Drain the oil while it's hot when you change it.

 

someone suggested run higher grade oil for 500miles so that the rings can seat. said probably 10w30 probably washed the cylinder walls.