Nope. I doubt gaskets are your problem. I use the same ones that you have (with the little blue round bead seal around the ports right?) and no problem at all. Felpro seem to be one of the best gaskets out there. Do you use your end seal gaskets (the cork ones)? If so then I recommend taking them out and not even using them, but two beads side by side of sylicone and you will be fine. First time I ever put gaskets on a manifold I used them and they leaked slowly, second time I accidentally hit the back one in, didn't know, started the motor up and oil all over the place and had to redo it. By that time 3 guys told me to not use them. I redid it with Felpro, didn't use the end seal gaskets and haven't ever had a problem yet. That doesn't mean that's your problem or nothing but I am just saying. I am still new to hot rodding and learning so I can't give you anymore info really on this subject or else I wont be 100% sure and I don't like doing that. I am very curious as to what is wrong with your motor, I will keep up with this thread for sure though. Take a break from it for a while, calm down and then maybe by a few more days you will have an answer.
Good luck man!