Are the 4-6 pages with low EPMV are all on the same topic as your higher EPMV articles? I looked into this for myself and found articles on Ezoic.com that mention looking at your overall content mix. Do you have other article topics/categories that pay more? If so, put more emphasis on those and try to produce more content in those categories.
The goal, I think, is to raise the overall EPMV. We may not be able to have enough effect on our existing articles to raise their individual EPMVs, but we can work to raise our overall EPMV. That may happen by writing more articles or posts in your other categories that are doing better. Or maybe it's not just other categories, but more of the particular type of articles that seem to do better on your particular site.
That is what I'm doing to override the effect that one high ranking but low EPMV article is having on my site. I've been working to write more content similar to those have higher EPMVs and it appears to be working. That low EPMV article still ranks #2, but the overall EPMV is rebounding.
Another thing to consider is the 80/20 rule. At least in my case, approximately 20% of my articles provide 80% of my income. Some just aren't going to perform as well as others or even as well as we think they should.
When you look at your Big Data Analytics to see which articles have high EPMVs, I would advise you to filter out results with just a few visits/month. It is possible to see an article that has a $40 EPMV but it only had one or two visits. Filter those out to get a more realistic view of your analytics.
You might get some more hints from this Ezoic blog post:
It's not a real quick process and you may think it isn't working. But we have to give Google time to work our articles through the algorithm until they are ranking pretty well.