Looking to buy a '96 Runner 5spd etc... Took it out for a spin and no major issues. Parked it and shut it off heard a noise coming from the engine compartment. Tried to search for the component online, but to no avail can't find it. On the driver's side is a large black plastic box with two round protrusions on top. Vac line coming from the air box and another connected to the vapour sensor on the firewall. Obviously some emissions deal. After shutting down the engine I could hear a brief buzzing noise out of the box every 15 seconds or so. After 10 min. no noise. Any ideas??? Sorry, but more familiar with the pre '96 models, thanks