I've recently ran into a problem with my motor, i went on a trip (not to long) it drove fine there and back but the next day when i went to start it up it ran horrible, i can't rev past 4100 rpm's and it feels powerless within those 4100 rpms that im allowed, i've got a jdm b16a w/ gsr tranny, chipped p28 ecu, i also have an apexi vafc, if anyone has any tips or has any idea what my problem is please help me out.

 

My friend's mom had that same problem with her Mercedes SUV, it wouldn't move very fast and had no power. It turned out to be something with the exhaust or cat converter. Could be that?

 

Why do you have two threads on this?