I hit a wall at full speed...

Over the last 4-6 weeks I've started to put real effort into my amazon affiliate site.

I've just finished up re-designing most of my pages to be more SEO friendly and to actually look more appealing and increase conversions.

I've been using a few methods of backlinking:
-1waylinks.net (automated blog network)
-3waylinks.net (automated link exchange site)
-Automatic Article Robot (Don't mass submit, do it day by day, week by week to keep things natural-ish looking)
-I have done a few squidoo plexo links in the past.

My site has done pretty well and is page 1 for two keywords and just outside page 1 for a third. However, I can't seem to climb any further up the ranks and feel that I've hit a wall. I want to break through it, I'm not getting enough traffic and I want it.

I'm thinking my backlinks aren't strong enough, or diverse enough.

Basically I was thinking I'd set up some backlink tiers as they seem to perhaps be stronger. I take it that it would be more beneficial to use my automated linking methods to create backlinks to pages where I have stronger backlinks ... such as:
-A squidoo lens
-A youtube video with link in description
-Some Ezine articles
-Some highish pr blog comments
-Any more suggestions?

Any other high pr links I could get I would also link to in a second tier from my current automated linking methods. But I think it's a good idea to also link a little directly to my site from the automated methods?

I'd love any input or suggestions.

Thanks,
Jason