could definately be an ecu issue also, as you know they are getting older and many are starting to go bad, especially if the problem comes and goes randomly, or when its hotter outside or the car has been warmed up a while. toyota tests it with a hairdryer near the outside of the ecu, and if getting hot causes the issue, its likely something inside the ecu, usually the capacitors have corroded and started to leak. again some ecu's are perfect and some are just really bad, have to test or open it up when its intermittent like that.