Niche site problems - Experience advice?

I have 4 niche sites ranked but two of them I bought. I'm trying to practice ranking a few micro niche sites before I build my better keyword sites. It seems like everytime I build a single link to one it disappears. I was on page 3 with one and built 2 tiers of links with a couple hand-spun articles and it hit the "sandbox." Ok, so I built too many links too quickly so the next one I just do an article submission to start and poof, it's gone now. Ok, so I'm thinking I have it figured out and start the next one with a few social bookmarks and the same thing happens. Wtf? The last one, I made one single backlink from a unique article that I wrote on Infobarrel and Google swept this site under the rug. Now, I'm thinking that it might have something to do with these sites having the same ip? Could this be the problem? Even if 2 of my niche sites that are ranked are from the same ip? I used the same wp theme and plugins for them all. Would that matter?
The sites are 2 pages of content and 5 pages of content and 2 of them are Amazon reviews. I've written all of the articles and reviews. I've followed the tips from here about internal linking, not too many affiliate links, having important pages like privacy and contact. I'm at a loss.

I have an older hosting account with another company. My best niche site is hosted there. Should I try building one there?