I dunno, sounds like the TPS is out of adjustment.

You talking about turbo'ing your NA? From what I hear, it isn't easy.
http://aaroncake.net/RX-7/naturbo.htm

 

A TPS out of whack would cause surging and other roughness. Try adjusting the air bypass screw on top of the throttle body. It's under a black rubber cap, and will just let more air in other than what the throttle plates allow. If that's backed out all the way, then tighten your throttle cable slightly. You can also try adjusting the variable resistor to either lean "L" or rich "R". Check the mazda manual for more info on these if you're unsure what you're looking at.

FSM available here:
http://mazdarx7.iougs.com/fsm.shtml