What is this

Hey ya all at tacoma world. New member here. Have been seaching thigs here for quite some time but never regestered. Glad ya all are here thought, been super helpful reading through forums in the past.
Anyhows, doing the head gaskets on my 97 4x4, which after i started, proved to be more than i wanted to do, but im into it now!! Good times.
While working the exhaust crossover pipe (i believe its called) this little plastic cylinder fell onto the driveway. I assume its a hose end of some sort, yet cant find the hose for it. I have marked all the hose and elec connections wit tape and numbers. Anyone have any idea what this is?

 

Looks like a filter cap for a vacuum switching valve

Something like this

 

BRO!! you nailed it, i was looking for a stray hose, but it is indeed an "vacuum switching valve"
Appreciate you, and the whole of tacoma world

 

Don't forget you can look at the vacuum hose diagram on the hood sticker

This is a 4runner from a Google search