pkosuru

Ours is 2008 Mazda CX9 AWD GT with 85k miles. Recently, we have started seeing transmission type problem. It happened between 2 &3 and 5&6 geears at speeds between 40 & 50, 60 & 70 at lower speeds also when at gear 3. It looked like some thing knocks or hesistates or jerks. The drive is not smooth. Some of the posts suggested spark plugs and/or ignition coil issue. Some youtube video suggested a shudder fix lube which was tried but did not help. The transmission shop did not find a problem and they said the transmission changed gears fine and commands looked good and suggested car performance/tuneup issue. So, I got spark plugs replaced at a shop and it is running fine so far.