Hello, I recently had my G28 engine speed sensor replaced because my 2004 A4 Quattro 1.8T kept dying when at stoplights. Now that the sensor is replaced the car starts better and has not died (also the check engine light has gone off). But now the car idles at 1200rpm when i first start it up when it used to idle at 800. The biggest problem overall is that the engine now lags and doesn't shift until I'm close to 3000rpm, and when I'm braking, the engine is slow to decelerate causing very weird downshifting. I would very much like some advice on what is going on because i am not much of a mechanic myself. Thank you.

 

hi, you can try clearing out the idle air control value with some carb cleaner as these can get gummed up and cause the engine to idle un-evenly.