I started to notice that my car kind of lags around 2500-3000 rpms. After that it runs through the tach like a bat out of hell. It's barely noticable when driving, but if I sit there and slowly give it gas at a stop it will go to about 2500-3000 and then kind of pause/lag. It seems like the timing is changing almost or like it can't get fuel fast enough. I have a JDM 10:1 engine with the stock intake and fuel injectors off of the old USDM motor that now have 223K on them as far as I know. I run 93 octane most of the time. I gave it a tune up around 215K. I thought about changing the plugs and fuel filter to see if that helped any. Also thought about running the diag. on the ECU (trouble codes) to see if anything comes up. If this doesn't work I'll just get the professional injector cleaner kit or send the injectors off to be Ultrasonically cleaned. I'll also clean out the intake by tearing it down. Any other suggestions?

Thanks,
Sterling