Dimming Lights

Last night I noticed that while at idle my interior and head lights dim or kinda flicker a bit. Its almost like a repeated pattern of a slight high and low. Its not very noticable but is this something to worry about? Would it be altenator or maybe the voltage regulator?

That is a common problem amongst these vans,(Silhouette, Montana,Venture.) You can read more about it and get more info from these links:http://www.automotiveforums.com/vbulletin/showthread.php?t=718039 ; http://www.automotiveforums.com/vbulletin/showthread.php?t=702783 .