2003 Accord Throttle Surging Problem/P0505

My 2003 Accord is experiencing a throttle surge problem similar to
what I have read about in this ng.  6 cyl.  No other apparent
problems.  120K on plugs.  27mpg.

It warms up OK.  Then it begins surging between 1000rpms to 2000rpms.
Up and down continuously surging.  It happens when it's sitting still
or when being driven.  Cruise on or off doesn't make a difference.
Using an Actron code reader I get a "pending"  P0505 (Idle Control
System Malfunction) which seems reasonable.  I don't know where to
start to address this problem.  Any advice would be greatly
appreciated.

Penthor