The previous owner told me he balanced the throttle bodies, however, in the interest of learning how to do this myself I purchased a Carbtune tool to help with this maintenance step.
The Carbtune allows you to view 4 of the TBs at the same time which I think is a big bonus in doing this maintenance vs. doing each TB individually.
They include some small orifice tubing to make restrictors otherwise the rods bounce up and down too much to get a reading. Since I already designed an inline restrictor for the gauges I sell I chose to use that instead
Plugs on the vacuum ports removed, lines plumbed in and connected to the Carbtune