My mixer revs up full bore and then quits, on any speed level

We need a Make and Model#.

1 gallon of 90w Gear Oil -- can be purchased from AUTOZONE! Make sure when you have completely drained from the large drain screw from under the mixer toward the back of where the attachments go on but not part of the part that spins around known as the Beater shaft! Once you have drained out all of the oil -- from the top where the front screw attaches the head or cap of the mixer -- add the oil there and make sure you are watching the sight glass to see when it is at the HALF way mark in other words when the oil level (TIP: Use a bright led flashlight to shine directly at this sight glass to view level) reaches to the midway mark of the oval sight glass, THEN STOP! It is full! Carefully start mixer on 1st gear and then 2nd so on and so forth to make sure everything is getting relubricated correctly and slowly -- don't just go setting it on 3rd or 4th speeds as you want to baby the mixer when you just put in new gear oil

Hope that helps!

You need a new Rheostat, it is central to the mixer chassis and the speed knobs one each side connect directly to it.

Obtain a copy of the Repair Part List for your model from Kitchenaid.com.
Download a Copy of the Kitchenaid Service manual.

http://www.kitchenaidparts.be/centers/servicemanual/mixer.pdf

First, you may want to adjust the mixer's speeds:

1. Loosen the lock nuts enough & Turn the 2 top screws clockwise until they cannot be turned
anymore. Leave the bottom screw alone for now.
2. Use a dab of white paint or paper whiteout to mark the positions of the Phillips screws.
3. Plug in your mixer and Set the speed selector to "Stir".
4. Turn each top screw One full turn couterclockwise (alternating between Left and Right)
Keep making one full turn at the time (for both left and right) until the motor starts running.
5. Put your hand near the Agitator shaft and allow it to brush your finger slightly. Use your
watch or clock and start counting the number of times the shaft touches your finger in
60 seconds. The correct count should be 60 RPM (Rounds Per Minute). If it is less
or more than 60, give each screw 1/4 turn counterclockwise or clockwise and start counting
again. Now tighten both lock nuts.
6. Set the speed selector to "6" and turn the bottom screw either clockwise or counterclockwise
to achieve a speed of 180 RPM.

For your reference, the planetary RPM's for the 5-qt. tilt-head Artisan Stand Mixer are as follows:
Stir speed - 60
Speed 2 - 95
Speed 4 - 135
Speed 6 - 180
Speed 8 - 225
Speed 10 - 280

Second, if the mixer won't run:
Remove the Control Plate Assembly (36), the Phase Control Board (39)
and the motor Governor Assembly (35). Inspect for loose connections,
burnt or damaged components. If they seem to look OK, re-assemble
them and test the mixer. If the motor still won't run, then I might suspect
a defective Phase Control Board (39).

By not working to mean that the planetary gear wont move? or does it just make a weird noise when it is on a low setting? If the gear is completely stripped the unit shouldn't run on any speed regardless if there is mixture in the bowl or not. Since I can't see the mixer I would say that there might be a slight tear in the gear which would only allow the mixer to get stuck on a slow speed where as on a high speed it is running fast enough to skip that particular tooth. I understand that the mixer is brand new but when it comes to mixers you can strip a gear right out of the box depending on the consistency of the batter you are mixing. If the machine is under a year old it is under warranty and you are allowed free service by an authorized repair center in your area.

your kitchen aid has a little device inside called the hall effect sensor. These often come dislodged or just stop functioning. If you are mechanically inclined you can replace this yourself.

It shouldn't do that, and I really doubt there's anything you can do about it other than to have the defective part replaced. It sounds to me as though there's a problem with the control mechanism. If the machine is still under warranty, contact Kitchenaid to see about getting it repaired or replaced. If not, get the name of a local shop that repairs Kitchenaid mixers -- from your description of the problem, the mixer is nearly unless in its current state.

The likely problem is the Hall Effect sensor located on top of the motor. This sensor is used to determine the speed of the motor. Since it does not sense a speed, the motor revs to top speed and shuts down. You have to shut the switch to Off/Reset to try again. Replace the sensor which costs under $10 before replacing the speed control which costs $50.

I replaced the control board on mine, and that seemed to resolve the issue

It could be the phase control, or it could be that the governor assembly or associated spring is missing or malfunctioning.