As to the vacuum lines, I personally recommend a two-fold approach. First, I prefer a detailed and thorough visual and physical review of all the vacuum lines.
Go ahead and start at the throttle body and feel and view each vacuum line, following them all the way to their terminal ends. That includes under the airbox and to the evap/charcoal cannister. Review each vaccum line in turn this same way. The common places for cracks and splits is at the rubber connectors. If you have any suspect connectors, I suggest replacing them all. It'* low cost and get'* the job done once and for all. All of the straight connectors can be replaced with a simple cut piece of rubber vacuum line purchased at your local parts store.
Even a small split or crack can cause more grief than would seem possible.
Second approach that many use is to spray some intake cleaner around all lines while the car is running and listen for any engine sound change. IMO, this is a secondary check and should not be substituted for the actual on-hands check mentioned above.
Mike: 1997 SE w/ 183K, aka White Horse
, Gutted Airbox w/K&N, drilled 180* t-stat, tint all around, clear corners w/SilverStars, "PONTIAC" light up tail, PEMs, NGK TR55s