Yeah this problem has been discussed here. Some of those motors are just poop. If you are already going in for the LCA issue, all the better. Just grab some time at the dealer and call it a day.
Can you describe your downshifting issue? Can't say I've heard of this one.
-2012 Grabber Blue GT 6M Premium w/ Brembos, Glass Roof, HID security pkg, Rear Camera, 401a, FRPP GT500 Axle-backs, Front Pioneer TS-D6802R speakers, JHR bracket, Bondra clutch extension.
-1986 Mazda RX-7 GX - Fast Mirage 16" Wheels, Sumo Firenza 205/60R Tires, slotted brakes + performance pads. Otherwise factory stock.
-2008 Mazda Mazda3 GT Sport - Stock, 5MT.
-2004 Volvo XC90 T5 - Comfort pkg, safety pkg.
-1995 Infiniti G20 - Sold, Pioneer head unit, lighting mods, miss it dearly.