[kyhoney44]

So I took my 2013 Limited Edition Hot Wheels Camaro to the dealership for a tune-up and inspection. They performed the multi-point inspection, an electrical system diagnosis, replaced plugs and wires, fuel induction service, cleaned air filter, changed out the tranny and rear differential fluids.
When I picked my car up, I drove about 20 miles, came to a stop light and as I slowed to a stop, my car kept wanting to lurch forward. I returned to the dealership on the following day and they fixed it in less than 15 minutes. They stated the idle was at 100% and that sometimes it takes a computer a minute to adjust?
After a couple weeks, I'm driving home from work and suddenly my car began to shake and idle very roughly. Multiple dash lights flashed and the Service Stabilitrak appeared on the dash panel. The car just stopped in the middle of the road. I had it towed back to the same dealership. They called to tell me there was a misfire on #5 and #8 and that there is NO compression on #8. The service department stated the technician went through the car to ensure it was nothing caused by their work. They said the technician stated a valve was likely bent and I needed to replace the engine at $8,700.
My thoughts are that they should've known if there was a misfire when it was in the shop. I did ask them at that time to go through the vehicle completely. How does a misfire on two cylinders occur so soon after this service?? I have never had any issues with my car in the past.