Car Jerk

I took my car into my normal shop yesterday because my Check Engine light had been on for a few days. When they called, they said I needed a new intake gasket and with a few other repairs, it would be about $450. I told them to go ahead with it, and when I picked up my car later (10 minutes before they closed) and drove it home, I realized that not only was my check engine light still on, BUT my car was jerking forward every few minutes. I called them immediately and they told me I probably shouldn’t drive it anywhere, but to bring it back in on Monday morning. Any ideas on what they did to my car? It was running fine before I took it in, I just wanted to know why the check engine light was on. Am I able to demand my money back AND have them fix the problem they created?

" Am I able to demand my money back AND have them fix the problem they created?"
No, you are not. How would that be fair.

What you can and should do is to demand that they fix whatever problem they have caused, at no additional expense to you. It may be a very simple fix like reconnecting a hose or electrical connector.