This article is from the Chrysler-Plymouth-Dodge FAQ, by Dr. David Zatz with numerous contributions by others.
Vaughn Smith suggests that, when you replace your rotor ($6 at a dealer),
you clean the Hall effect pickup (just under the rotor, you can't miss
it!). This helped him quite a bit on three cars. Be careful to put it back
the exact same way it was when you took it out! Also clean under and around