I just bought a used 99 Passat V6 with 74K on it. The engines is idling rough like it is miss firing.

The place I bought the car from changed out the spark plugs and the plug wires but the problem is still there.

Any idea what could be the problem? They ran a computer diagnostics and scanned the codes, but nothing came up.

Also, when I'm accelerating, the engine feels like it is lacking power at low rpm. Since I just got the car, I don't really know if this is just the way the car is or there is something wrong (related to rough idling??).

What I do know is compared to a 01 Jetta V6 I drove, the Jetta had a lot more low end power.

Thanks for any help.

Check the coil packs or just replace them. Try buying them online at ecstuning.com . Good luck

Also, commonly the MAF can be out of calibration. It won't necessarily set codes either. The only way to see it is to take it to someone familiar with using a VAG scanner or simulator. You can read the measuring blocks & see if it calculating air volume correctly.