Mazda 6 Service Manual: No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

No.19 excessive shift shock on torque converter clutch (tcc)

No.21 noise occurs at idle when vehicle is stopped in d, s, l ranges, or in r position

Other materials:

Mazda 6 Service Manual: Recommendations for Shifting
Upshifting For normal acceleration and cruising, Mazda recommends these shift points: *1 Always observe local speed limit regulations. Downshifting When you must slow down in heavy traffic or on a steep upgrade, downshift before the engine starts to overwork. This gives better acceleration w ...

Mazda 6 Service Manual: Cruise control switch inspection
1. Disconnect the negative battery cable. 2. Remove the driver-side air bag module. (See DRIVER-SIDE AIR BAG MODULE REMOVAL/INSTALLATION.) 3. Disconnect the cruise control switch connector. 4. Inspect for resistance and continuity between the cruise control switch terminals using an ohmmeter. ...