When my 2003 Tacoma is started cold (under 45° outside temp), it makes a rapping noise as I start driving. The noise lasts for about 1/10 mile or so, then stops. Does NOT make the noise when the clutch is disengaged or the transmission in neutral, or if the truck is coasting with no throttle input (either in or out of gear). Does NOT make the noise if I simply “rev” the engine, either. Anybody have any theories?