For the keywords you are targeting check who are in the first places. Then copy what they are doing, in terms of backlinks, frequency of updations, etc. etc.
pagerank does not have anything to do with traffics. if you want to have more traffic you should work more on your search results in google and yahoo.
Traffic does not come with PR. I have High PR getting barely anytraffic and PR n/a that gets thousands of UV's.
I would say, increase your overall visibility in the web. First, check out the keywords you are targeting to see whether they need to be reconsidered or something. Second, revise the content of your site and check its SE compatibility. Third, build links by whatever means you can. Fourth, remember to analyze your activities and change priorities whenever necessary. Fifth, keep on learning.
Try to find your keywords in Google Trends - maybe this will show you if there wasn't some kind of drop down in the searching results - someone suggested it before but maybe people are really not looking for this stuff anymore.
As they said, do not rely that much on PR, I have a pr1 with like 3 uniques a day. Rely in keywords and backlinks, but be careful not to build them too soon.
The onlt reason anyone would care about PR is if he is in the link selling business. Either than that just ignore it. As for your traffic problem, there is much information on how to drive more traffic to your site on this forum.