What could cause the RPM gauge to go up and down while driving?
That's called the tachometer. You didn't provide much information, but maybe it only happens when you (or the automatic transmission, if you have an automatic) shift gears. If that's the case, it's normal. Shifting to a different gear at any given speed changes the RPM's of the engine. If it happens at times other than when shifting, something else is wrong.
What would cause an RPM gauge to go nutty in a 1989 Chrysler LeBaron while the car is still driving fine?
Why1998 S-10 gauge lights come on while driving seems to lose power Goes out security light stays on?
This is different in different states, but your driving privileges could be revoked for too many tickets, multiple wrecks, driving while drunk, driving while texting, driving without insurance, committing a felony while driving, leaving the scene of an accident, running from police, failure to appear in court to answer for a ticket