my boy has a 2000 honda accord lx 4cyl auto and it has a stock intake but we removed the bottom box below intake filter that is in the fender and now it wont rev past 5k and it feels flat when he jumps on it.... the car feels like it has no power compared to stock, however it ran fine for like a week after we removed it but now it is flat as hell.... we reset the computer and also changed the spark plugs and it still wont rev, even in neutral it wont rev past 5k....... any suggestions would be appreciated

 

it have nothing to do with the intake.

there's no sensor or nothing on the air sonator(the air box you mentioned above)