my d15b timing belt squeels every once in a while. and everytime it does i think it messes up my timing. What i see happening is that the belt is actually rubbing against the plastic cover in the side of the motor. the belt came out of my old d16z6. I have a D15b7 belt, will that work? I s the belt too thick or what? Also it idles at like 1500 to 2 sometimes. And other times its fine at 600 or 700. What can i do?