 speedometer going crazy
just recently the speedometer needle on my van started acting crazy. sometimes the needle jumps around while i'm driving a steady speed, and usually when this happens it will drop down all the way to 0 mph, all while the car is still in motion. after a short time, it will begin acting normal again.
does this completely intermittantly. seems to happen most when i'm traveling at slower speeds 30 mph or less, although it has happened on the freeway too. the good thing is that no other guages are doing this, and the engine and transmission still seem to operate normally while all this is going on. the bad news is that it's extremely annoying and it will probably get me pulled over soon without having a properly functioning speedometer to rely upon.
anyone else experience this problem? any thoughts?
i think there is a speed sensor onn each front wheel, should i start by checking those? | 
