Cleverusername

Hi. I'm new. I have a stock 95z28 camaro. I have been having issues with it recently.

Issues:
Service engine light comes on while driving, but turns off when stopped
My speedometer works most of the times, but sometimes I will stop at a light the car will act funny and then it goes out
Rides rough sometimes but not all the time
Random misfires


Suggestions? I have brought it to 3 places but can't find anyone who knows a camaro from their ***. I'm thinking optispark but that's a lot of work and money not being 100% sure it will fix the problem

Thanks ahead of time.