Need some help, got an 03 6 speed base model. Will randomly have an unresponsive throttle only while in gear or with the clutch pressed. If I take it out of gear and let out the clutch it will respond but if I put it back in gear it still is unresponsive. Note there are no codes or TCS or slip light due to it being a base model. Also clutch is not slipping at all.

 

I would check the tail lights first, I bad bolt can trigger throttle cut. Next would be the brake light switch checking.