Stage 2 cams per SHM site says they are a .474 intake .452 exhaust and 235/225 duration. The large of a cam requires a stronger spring. You running stock springs? Were the cams degreed or just replaced back to original settings? If installed incorrect you could have retarded the cam timing worse that what it was and have a loss of power. However those cams will most likely raise your peak rpm power (if installed correctly) and the intake probably isn't moving enough air for those cams but you still should have made more power in any range over stock cams.

99+ intakes won't work with your b-heads. What you need is a shortrunner b-headed intake. That will compliment those cams. But I'd pull a valve cover first to see if you have a broken spring. Then if not do a compression test. If the numbers are low it could be the cam timing.

Hope this helps. Oh btw, I happen to make custom shortrunners for the b-heads.

-Mark