I have no idea what could be going on. I have a 199 Honda Civic with the 1.6 SOHC Vtec (D16Z6) from a 1995 Honda Civic in it. When i floor it, it will not go past 5000RPM, its like it hits a rev limit and the whole car just haults. And for a little while after that it is extremely slow and after a bit it will pick up. I have no clue what the problem could be. My check engine light is on but is reading code 41 which would be the primary O2 sensor, which i cant figure that out b/c the OBD2 requires 2 and OBD1 requires 1, and i just got the one replaced with a OEM Bosch replacement. I dont think the O2 sensor problem is causing this but not sure please help. Thank You.

 

any other codes? sounds like it's not getting enough gas in around that 5000 rpm. it could be the O2 sensor, i cant be sure.