BMW 323ci 200 Automatic

Recently took my car into get serviced to fix the thermostat and get an inspection. Before I took the car in everything was running great except the heat. My car passed inspection with no problems. After picking my vehicle up it began to run poorly. I am experiencing what feels like I am driving over a bump for the first split second or so as I step on the gas. It feels as if the fuel is not making it to the engine and the car is “coughing”. Can anyone out there offer up some advice? I am sick of getting ripped off from mechanics.