From VFRwiki
This is an issue that plagues the VTEC engine (Gen 6). Countless hours have been spent to attempt to sort out or stabilize the issue. Problems reported are surging at idle or lower RPM's, as well as low RPM hesitation. Some have attested that the Pair Valve Blockoff has calmed the VTEC transition as well. The issue does not effect all machines nor is it pin pointable to any machine. It appears that the newer Gen 6 VFR's have had minor corrections to this issue.
The following links take you to the engine section of this Wiki to possible fixes.
