Car bucking or hiccups while driving

Engine light was on at dealership when I bought the car. They said it was something unplugged and it corrected when they plugged it in. Then my A/C started going cold to hot and later the same day my car started bucking or jerking while driving and I had it towed. Mechanic doing a diagnosis said I never should have bought the car from dealer he counts 8 codes and it’s leaking coolant (not sure yet if he meant transmission or A/C) and it got up to 250 degrees. I’m going to talk to him tomorrow.