Car won't go below 3k and won't accelerate
 

I have a na 88 gxl with a air pump block off and straight piped with 2 1/2 in exhaust. other than that its all stock. I bought the car and it wasn't running. It still won't run right. I've replaced the injectors and checked the CAS and the coils. I also replaced the AFM because the old one's resistance was off. It has new plugs, wires, oil, everything. I can't check the timing because it won't run blow 3k rpms. It also takes like 30 seconds to get to 30 in first when your driving. When I'm sitting in my drive way it can rev the piss out of it. it will hit 10k+ with no problem and really quickly. I've been on this forum for 2 months looking for a fix but I've found nothing so far and no one has been able to help me. I really don't want to but I've been thinking about a swap with a v6 but I don't want to loose the rotary fun of the car. If anyone can help me it would be greatly appreciated.