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.