Blinking headlights/dashlights

I've posted about this before, but have so far struck out. My 02 Impala LS gets into this mode every so often where the headlights/dashlights will
blink on and off continuously (about 1 blink/second) when I decelerate.
The dealership has given me the standard line about it being the AIR pump and this is considered normal. I can live with an occasional momentary dimming, but that's not what happens. When this happens, the lights blink continuously until I either step on the gas or come to a complete stop.
I found this page: http://www.gmproblems.com/headlights.htm that describes an alternator problem that sounds like it might be the cause - does anyone have any detailed information on what alternators are affected, how to determine if my car has one of them, and what replacement alternator is best? I'm willing to buy/install it myself if I can just get enough info to make an informed purchase.
Does the AIR pump ever legitimately get into a "rapid cycling" mode? What is it for and how often does it normally cycle on and off and under what conditions?
Thanks!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Maybe you have the police option. You're not accidetally hitting the overheads by mistake are you?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.