my 98 neon's speedometer will work fine when i first start the car, for about 5 minutes or so.
however, after that, it starts to bounce from 0 to 20 like a madman, then finally just stops moving altogether at 0.

what is this? i seriously just got my car back less than a week ago for transmission and alignment problems.

I got the same problem... Except it's 30 down to 0... And it was real great... I was entering a turn, I normally glance at my speed and I started flipping out! I thought my brakes we're going to go, but they didn't, so I had to guess my speed... It has been off and on all night... Really pissing me off... Then some lady scratched my car! Hasn't been a good neon night.

may want to try this sight...good luck, the fix was easy for me...

http://www.neons.org/modules/news/article.php?storyid=18

same exact problem here...pissed me off so bad after trying to fix it i just got one from a junk yard for 25 bucks and never happened again.

it could be battery problems... i had a 95 neon, i was just driving down the road and the gauges started jumping. the car would still start and the radio and dome light would work but i found out it was the battery and after i replaced it everything was fine... might be a good idea to check yours..