Hello everyone, first post here.
I have a 1994 XJS 5 speed (factory) which is giving me this problem....when I accelerate in any gear when the engine reaches around 3200 RPM the car begins to shake and the car stops accelerating almost as if power was cut off and it will do this until I shift up to the next gear then all is normal until I get to around 3200 RPM again and the cycle repeats itself.
Other than this everything else runs normal.
Also worth mention that the check engine light came on with an FF23 code (O2 sensor).
Any opinions on what can possibly cause the car to behave this way? Any and all opinions are welcomed.

 

My 97 XJR acted this way until it finally quit. It isn't a manual trans, but would not run over about 3000 rpm. It showed about 4 codes, but wound up being the crank sensor.