Hi , I have a 2012 sr Hilux dual cab auto it has been giving similar problems from the start, I have had a ECU up grade ,and that worked for a period but with just a four wheel motor bike in the back it will have a fit now and then change from 3rd to forth back and forward, if I slow down (80Km) for a while or stop and switch it off and start again it will go back to pulling top gear for a while It also spits oil out the trans breather,If I tow a small 6+4 box trailer with only 350kg it will never lock the converter ,in fact the slightest head wind when it is empty it will not lock the converter..I have complained at the dealer but all when they test the ECU there are no error codes.The last correspondence I have had is they want to do some tests.Apparently they have never herd of these problems.They also recommended that at my expense they would fit a transmission cooler,You buy a 55000+ car and start fixing it at your own expense?I refused it should be standard!!!Please let me know if you have any success with solving the problem.CHEERS