When my '04 New Beetle Convertible warms up, the car jerks to a stop when applying the brake. It also jerks when I step on the gas. Once it's moving, it runs fine. The check engine light is on as is the deployed airbag light. I put gas filter cleaner in the tank, use premium gas (shell) but it still hesitates and jerks. When the car is cold I don't have a problem with it. Was going to put two bottles of fuel injector cleaner in the tank.....any suggestions?