Vacuum leak/component location

That is the idle air control valve. It is a simple bolt on part with a gasket between it and the intake tube. The piece that's missing is a small inlet filter. However if it was leaking smoke from that port the internal valve seal is bad and the valve needs to be replaced. It's a simple job, disconnect the electrical connector, then remove the two bolts and remove the valve, clean up the surface and install the new valve and gasket. The bolts get torqued to 7.4 ft lb.
Reinstall the electrical connector and it should correct things. Be sure you get the same type of valve as they made three different types for that engine size.

Replace the IAC valve itself. It shouldn't show smoke at that port because of the internal seals. A way you could verify that the vacuum leak at that valve is the issue would be to plug that hole with a rubber plug, then see if it runs better. You won't want to drive it that way as the vent is needed but for testing it will be okay. Then just replace it as noted in my other post, remove the two bolts, clean off the surface and install the replacement. Be sure you get the correct replacement as there are three different styles and they do not interchange.

No problem, let us know what you find.