it's coming from the engine compartment.
the motor doesn't smooth out when driving. i notice a little bit lack of power. the noise / vibration is the worst in reverse and drive. it smooths out in park and neutral.
i will smell check the gas.
a buddy of mine that's a mechanic also suggested checking the distributor for water. it's been raining a ton lately, and the car pretty much sits outside. he said to pull the distributor cap, spray it with some brake cleaner and make sure the contacts are clean. and to check the rotor for water as well. he thinks one or a few cylinders may not be firing.