I've used this paper, about a 100 box worth, and I find that I don't like it with lith developers. I've used Maco Superlith as well as AristaLith liquid and AristaLith powder (from Freestyle) and I cannot get black out of the paper.
With that said, I've never seen the results you're having. I've always had evenly developed paper. I had some problems with Kentmere Kentona once where it was fine with regular chemistry, but exhibited problems with lith. I sometimes think that lith chemistry brings out both the best qualities and the worst qualities of paper - but you can never really tell when.
I concluded that this paper is best used with standard b&w chemistry, (I use Ansco 130 and Ilford Multigrade), where I can achieve a strong black and make that texture work for me.
Other Foma papers, like Fomabrom 112 and Fomatone 132 are, in my opinion, much better suited to lith printing.