88 anniversary turbo II won't tach up need help!!!!!

Hi I have a 1988 Turbo II Rx-7 and when I bought it, it was not running, it has like everything possible for after market parts on it and supposidly a JDM engine. I changed the main wiring harness and now it starts up but when you hit the gas it only tachs up to like 3 grand and then just pulsates around 3, but if you just barrly hit the gas it will tach like there is no tommorow I dont get it. The timing is set right my only guess is that maybe the secondary injectors arent working, but i am stupid when it comes to these things, if anyone could tell me what is goin on i would really appreciate it.