Help please
 

I have an audi cabriolet 1998 2.8 v6. The engine is running rough and idling low. I have replaced breather hoses and air vacuum hoses and new battery but still getting these problems...any help please?

What's the last time you did plugs? Have you cleaned the MAF lately? Do you have a Check Engine Light?

Have you done a throttle calibration? Your battery was out, and it probably needs to be reset. Your car is a cable-driven throttle car but it'll still make a difference. Search for "throttle body alignment" for instructions.

My '96 is cable-throttle and has never had idle issues due to the battery being disconnected, although it doesn't have a motor-throttle idle control like the '98. But we also have a '99 Passat 1.8T with the motorized throttle, and also never any particular battery-change issues that I can remember. My guess it that an adaption isn't going to fix rough running. Something else is wrong, and a code scan is where to start.