I own a 1998 4cy 4dr auto. accord and for the past 3 years if feel that some days my car runs so smooth and picks up fast but there is days that it runs sluggish like if feel that i have to punch it more....i have also noticed preformance diffrence at different gas levels...the car seems to pick up faster when the gas level is right before the half way then when is full.... could it be a sensor that is bad that makes the car feel that way???