How to repair engine vibration especially on idling

How to repair Hyundai,engine vibration on idling.?

Model: Hyundai Elantra HD
Year Model: 2009
Fuel : Gasoline
Displacement:2000cc
Subject:Engine vibration on Idling

1) Condition

1. Engine excessive vibration on idling.

2) Cause

1. Due to excessive spark plug gap clearance.

3) Diagnosis

1. Scan tool check
   = no trouble found.
   
2. Check the Fuel pressure by using GDS Actuation test.
   =The pressure ok.
   
3. Check the spark of spark plug one by one.
   =OK
   
4. High tension wire.
   = Ok
   
5. Check the spark plug.
   = #1 and #2 has excessive clearance.

4) Parts Replace

1. Replace with new spark plug, the problem occurred immediate.

more case & please leave as comments