Have you had where you’ve just bought a domain with high pagerank (above 3) and then in a few days after you maintaince the domain then have pagerank drop?
Remember, that the most important factor is the Page Rank backlinks, the previous domain user must also have a content, and of course a few backlinks to that domain makes PR 3 or more blessed by Google. Well, when the domain changed hands, automatically changing content, changing permalink structure, so the Google crawler will reanalyze when visiting your blog. Well, as a result backlinks will start from new, and there is the possibility of your domain homework will be reduced even start from scratch.
Interested? come on go to next step..
Following the way I did and could increase the chances of maintaining Page Rank domain.
1. Add a backlink from social bookmark and web directory as much as possible and as soon as possible. For social bookmarking, use the Social Marker (http://www.socialmarker.com) which will facilitate you to submits.
2. Link Exchange. The trick is as follows, go to the Forum DP (http://forums.digitalpoint.com) And go to the Link Exchange. Take the most advantage, Remember! Your property is now a PR 3 or more.. Tens or even hundreds of sites ready to exchange links with you.
Following rules:
* Look for sites that have same related with your site.
* Look for sites that have PR 3 and above (you have not also PR 3). You are the most benefit here, because usually PR 3 sites that you find in the forum has been established and stable:)
* Take your signature link with your new domain 
it’s very powerfull trick to make your site listed by seacrh engine
Hope this work!