White smoke from the exhaust is a sign of coolant in the combustion chamber, and can be a blown head gasket or cracked head. This is very serious and will cause severe engine damage. Have this looked at by a professional. A slight jerking motion in the front while accelerating is possibly torque steer. This is normal. Check this out after dealing with the white smoke, which at this point is your first priority.
When an ignition coil goes bad the car will not run right, or not at all. An intermittent coil will cause shudder, or a jerking motion. When the coil has no output then the cylinder that the coil feeds cant burn the fuel and cause power.
There are many things that can cause this problem in a car. A bad O2 sensor, or even a bad part in the fuel system. (fuel pump, filter or injectors)
The primary cause for jerking on a 99 Mercury Cougar is the engine not getting enough fuel. This can be a sign of a clogged fuel filter, bad fuel pump, or clogged fuel injectors.
Jerking in your sleep, may be Restless Leg Syndrome. This is not uncommon with Fibromyalgia, but it may also be a side effect of some of the medications commonly prescribed for Fibromyalgia. If you are experiences jerking in your sleep, you should report this to your doctor to determine the cause.
It could be several things but if it is a constant jerking (repeating) and more noticeable a lower speeds < maybe even pulling to one side ,where you have to hold the wheel a little to the other direction to go straight. I would suspect a bad tire , may not be noticeable just looking at the tire but could have a internal broken belt.
Have the system checked for codes, that will lead you to the cause.
yes they do
yes
Check your motor mounts and what your at it check trans mounts.
It definitely is a possible cause of it jerking, if it's not an engine mount, service the transmission
They can cause both emotional and physical pain (such as head jerking or jaw snapping)