the noise you are hearing is the engine vent valve. it's located further back, near the firewall for the driver side. I've had that noise before and after replacing the valve, it never happened again. that part is around $6
This. I found another thread which goes into detail how to replace this valve (it's called the PCV valve):
https://www.yotatech.com/f117/pcv-valve-location-swap-4th-gen-4runner-292958/
