Hey guys I'm new to this site. I own a 2000 Honda a Civic Si with a B16A3 stock engine. It has about 161k miles on it. A problem I'm having as that when it gets to about 2500-3000 rpms it seems to hesitate like something is holding it back from accelerating. I just recently replaced the O2 sensor hoping that it would solve the problem. I'm not sure if it's just the engine getting old or something else. Any tips?

 

nice 1

 

Do a full tune up. Check ignition and mechanical timing.