Could my msd 6AL box be the problem????

I have a 1991 H.O motor with aluminum heads, longtube headers, F303 cam, typhoon upper and lower intake, and msd (dizzy,coil,6AL box) and 5speed transmission. For some reason i can not go past 3500 rpms, what could be the cause of this and what can I do to fix this problem? I just replaced my fuel regulator because a few people said i might not be getting the right pressure, so i changed it to a holley adjustable one and the problem is still there... So now i am wondering if it is more of a ign problem. So now i am wondering if it could be my msd box what do you think?

yea i see i need to recheck some things.I have a msd coil that does not have the slot for the harness. I did a efi swap in a 64 1/2 mustang so things are a little different. But i am going to check out the box to make sure there isnt a small chip in it

ok thanks, i will try that