Look for Vaccum Leak. Also may be bad plug wires or coil good test for this is wait till dark and use spray botle of water, spray lightly over wires and coil. If this does not work check all your engine grounds, if old replace. If Ford it has to have at least three. Good Luck.
Either the Hard Drive spinning or a fan.
inspect the upper motor mount
rubber bushings in motor mount worn
Most likely issue is a motor mount collapsed. The second most likely is a misfire.
your shift solenoid a is stuck open in your tranny time for a gagage visit
It would be good if you stated what kind of car and trans you have. It can be either engine or trans mounts especially if it is front wheel drive. Have it checked out. GoodluckJoe
Unless it is caused by pavement or road conditions, the likely causes are:Tires out of balanceTires bouncing due to worn shock absorbersUnevenly worn tires with "cupping" at the edgesWorn out U-joints in the drive shaftLoose lug nuts on wheelsWorn U-joints in the drive shaft become more noticeable the faster the vehicle is traveling, and the vibration will still be present if the transmission is shifted into neutral or the clutch is disengaged, allowing the truck to coast.
Possible bad motor mount
What is it?
Most vehicles will not allow you to shift from neutral or park into drive unless you have your foot on the brake. It is a pretty simple logic flow in the car's computer.
if its a manual transmission in neutral and 4 wheel drive in neutral with brake off. if its an automatic you will have to pull the drive line to rear wheels and place 4 wheel drive in neutral with brake off.
Bad axel shaft u-joints. U-joints bad in the front driveshaft. It would really help to know the year.