Just started happening... When Im sitting at a light with my foot on the brake I can feel a "bump..bump...bump" like its going with the idle of the car. I put my foot on the clutch just enough to take the slack off the cable it stops.... So today I tightned the cable with the firewall adjuster and it didnt help. What could cause this? Ive never known "clutch chatter" would this be it? Where would yall start looking?