My 1996 Audi A4 1.8 always starts when cold, without pressing the gas pedal. But when the engine has been run the engine turns over but it then struggles to fire up. Once the engine is running the idle speed is uneven and there is hesitation when first accellerating in 1st gear. There is also a mysterious high pitched chirping sound from the engine whilst at idle speed and the exhaust tail pipe sprays out water, even after driving on a long trip. "Please Help"