Engine misfires at 3K only?
 

I have a 89 Dx with a b16a Obd-0 stock everything on the motor. The problem I have been having is that at 3K rpm exactly it misfires constantly. This only happens at 3K any other rpm it runs fine. Right now the Tps is disconnected, when I hook it up the problem gets worse it will misfire throughout the rpm range. I already tried replacing the tps( bought a new throttle body) and got the same problem. Also I cleaned and tightned the FITV valve and replaced the IACV valve, with the same results. I checked the ignition timing dead on, cap and rotor are also in good condition, I got the distributor new from distributor king like a year ago. The only other problem I can think of is that I had a intermmitent O2 sensor CEL, but I think it was due to the wiring which i fixed and I havent seen it for about 2 months. Any thoughts or suggestions on which direction I should go next would be appreciated.