1998 Audi A6 slow acceleration no power on hills

SOURCE: 1998 audi a6 air filter change

If it's the 2.8L V6, the air filter is in the big plastic box on the passenger side of the engine bay, between the back of the headlight and the secondary firewall that walls off the engine compartment from the battery compartment. Just undo the clips holding the lid onto the box, lift the lid, and you'll see the filter inside.

SOURCE: no acceleration,audi 1.8t,runs like no boost

have you tried cleaning out the throttle body as i had a similar problem and this worked

SOURCE: thermostat audi a6

look under car on water pump housing, the thermostat is on a metal housing that looks like an igloo and has to bolts perhaps 10mm or 13mm, and an "O" ring in between

SOURCE: where is the thermostat located on 1998 audi a6

The thermostat is located on the pass side of the engine.  There are timing belt covers that need to be removed.  In order to remove the thermostat normally the front bumper has to come off and the car has to be put into what audi calls service mode. This allows room to get to the timing belt components.

SOURCE: AUDI A6 WINDOW PROBLEMS

This is a common problem with the C5 A6 models. Before you replace the fuse for the windows (I think it's number 14, but i don't have a manual in front of me - Anyway, it's the 10A fuse that's blown!) Look under the back of both front seats and you'll see a light that illuminates the floor for the back seats. Rem ove the light from each seat by prying it out with a flat screwdriver and disconnect both leads. Replace the fuse, and your windows (moon roof and interior lights as well) should now work. The lumbar support causes something to short out the lights. I've tried insulating the lights on mine, but the problem always comes back so I just disconnected them altogether.