Why is my spedometer bouncing, ABS light is on, Service engine light is on, Trac OFF light on?

as tom says all related,if you have money to throw at it and in a hurry a good guess would be the rear speed sensor ,a magnetic tipped device measureing the each spin of the final output of drive line ,sometimes just greese on tip20% ,usally held by one # 10 mm bolt r r and reset light

I would say that you have two problems. The one is a bad front wheel speed sensor that is turning on the "Trac off"/ "ABS"/ "Service Vehicle Soon" (not CEL, it's often misreported). That's a common problem with the Grand AM/Alero/N body platform and I'm climbing out on a limb inferring that. Get the codes read like Tom said to confirm it. --- The bouncing speedometer needle is one I haven't heard of.

I just experienced a similar issue. Car began stuttering, Trac off light and Service Engine Soon light came on (but not ABS light). Got the car home, added fluids (which were very low) and the car seems to be running fine now. But the Service Engine light is still on. The code is P0304 which is Cylinder 4 Misfire Detected. I guess I'll reset and hope the problem does not repeat.