Schiller Welch Allyn Cardiovit At 2 Interpretive Ekg Machine "2001 audi a4 quattro replace" Questions

2001 audi a4 CEL came on hello i have a problem with my 2001 audi a4 1.8t quattro ...my engine check light came on flashing and the car run really rough and engine shaking like 1 of the cylinder is ...