I have a 1993 ford taurus 3.8L V6 automatic GL. If you think you might have a “vacuum leak” then how would you check for it?
The easiest way IMHO is with a vacuum gauge. They’re cheap, installed in a minute, and will show you right off the bat if you have a leak or not without any guesswork.
A vacuum gauge should be connected to an intake manifold vacuum port below the throttle plates. It may require a plastic T-fitting to splice in to an existing vacuum hose, but many vacuum gauges are sold as a kit and may have an assortment of fittings for use on different sizes of hose.
The usual symptoms of a vacuum leak may be a rough idle or surging at speed; depending on where the leak is and how severe it is.
The EGR valve and Idle Air Valve are actually vacuum leaks - just controlled ones.
And check to see if any vacuum is being lost from a hose or vacuum controlled component. Disconnect each vacuum hose. With the engine idling, plug the hole to the engine, and note if there are any changes to the idle. If there is, that vacuum hose/component is probably leaking vacuum.