I have a 2006 Mazda 5 Sport with the 4 speed automatic transmission. For the last several thousand miles when the transmission is not at normal operating temperature (read: morning start up or after cooling down) and while driving, the transmission will randomly down shift from 4th gear into 3rd gear and stick there. If I pull over and come to a complete stop the transmission will reset itself, usually, and I can proceed without any problems, as long as the transmission is warmed up enough. If it is not I will have to go through the same scenario all over again, sometimes two or there times. Sometimes, to get the transmission to reset I have to turn the car off and restart it. After the transmission resets, if sufficiently warm, it will function properly all day from many many miles. I drive very long distances with this car and have over 200K on it. The transmission has been running Royal Purple ATF for the last 50K miles or so and the transmission is serviced very regularly. I own and a custom vehicle shop and suspect it is a solenoid malfunctioning? Someone suggested running additional ground wires and we did that with no change. Anyone have an idea how to fix this without a complete transmission change? Thanks.