Rankings dropped after putting up Amazon links

A few days ago I placed some links to Amazon on a few of my sites (these are micro niche sites that are 6-12 months old), and now the rankings that've been stable for months suddenly dropped.

The links are incontent ones about related products, and I even tried to cloak them with the Pretty Links plugin.

The drops are nothing major, only a few spots, but it means a lot when you're on the upper half of page one. For example one site got from #1 to #4 and another from #3 to #6.

Could this drop be related to the Amazon links (because I think I read something similar a few months ago, though I'm not sure), or maybe the plugin?

What's the best way to link to related products from your articles in terms of SEO?

Thanks!

try using redirects rather than affiliate links

What kind of redirects do you mean? Do I need a seperate domain name for that?

As a test, I removed the links from one of the sites, we'll see if it'll get back up in the Serps. In the meantime I'd appreciate any insight that might anyone have regarding the subject.

Thanks!

-Make sure your plugin doesn't have a footprint
-Try not to use the iframes
-Don't spam your ads all over every inch. Try 2 adsense and 1 amazon limit the total at max of 3
-content to add character ratio, At least 4 times more content characters over coded characters
-Make sure you have the contact, about and privacy policy pages up