I'm experiencing the same thing, while the pr of one of my websites went from 0 to 2 the SERP decreased. I used to rank 2 for the natural keyword "yamaha forum" now i'm 5th. I'm not sure why and if google will give me back my position.
For the few search phrases I follow, it seems that wikipedia has moved slightly higher in the past few days. That suggests to me that older high traffic sites are up and younger lower traffic sites are down, slightly. This may be an algo tweak. If so, I hope they roll it back because it seems that old 'junk' sites are the winners here.
In my own experiences, a PR drop would usually come with a penalty if you link to some bad neighbors. So, I think you might want to check your on-page issues to see if you have some black or gray methods to promote your sites. Have a nice day,
My site's pr go from 0 to 1, many keywords have better ranking now, and my competitor's pr decreased from 3 to 2, my ranking is better than its now.
I have been saying this for years, PR has NOTHING to do with your SERP(s) or your ranking. PR is just a number, that means nothing. I have PR0 Sites that are on the first page for competitive terms, and P3 sites that can not be found in the top 10 pages for their main keyword. PR means nothing, and will not make or break you in anyway shape or form. Focus on your rankings, and forget about PR. It doesn't have to mean that at all, it could simply mean you used to have a link from a PR5 site, and they removed your link, or that site lost PR and now you have less PR. One PR5 link can be the difference between PR 2 and PR4. PR is meaningless, yet it keeps so many peoples brain busy they forget what is truly important, rankings and traffic. Focus on rankings and traffic, if you get PR too, great, if you don't, who cares -- because you already have rankings and traffic.
PR & SERP are not always linked.Backlinks are an essential piece to optimizing for better search results.so be consistent and get backlinks on a regular basis.