Does anyone know what this could be. My 98 Ford Explorer Sprt (190K) makes a noise that sounds like a playing card placed in bicycle spokes (on the left side) everytime I push the accelorator to speed up or take off from a stand still. I haven't gone to the dealer just yet, just looking for any input on what this could possilbly be. One co-worker hinted that it could be a problem with the exhaust manifold. Any thoughts.