try sitting in your driveway in 1st gear and letting out the clutch very slowly and if you can let off the clutch completley or it's way off the floor your clutch is probably about to go. and i think i know the feeling your talking about. sort of like a hesitation i think? could be your plugs or wires or you could have a leak somwhere that you don't feel under low boost but you can feel while boosting high.