1998Honda Accord v6 Vacuum leak locations

Vacuum leaks would seem to raise the vehicle idle, not cause shaking while idling and loping when giving gas. I would probably seek guidance from someone with a diagnostic tool capable of monitoring data so that you can see what area your concern lies in. Did you replace the ignition components for a purpose other than regular maintenance? A MAP sensor reading can be quite helpful in determining if you may have a valve clearance issue as well -- these vehicles should have valve adjustments performed when performing spark plug replacement and timing belt replacement (typically all due at the same time).

Recommend 'complete' - professional scan test - that will include live data monitoring of multiple parameters which should reveal area of required *hands-on* testing.