Although there was no accident with our two encounters of this problem, we now cannot trust our much-loved Sienna. Fortunately, we live in a rural area, and when this occurred, there was little danger of loss of control. (My wife would disagree about this, but, as the driver, she handled herself well under the pressure of the unexpected.) I was driving at the time of the second occurrence, and quickly saw that what I expected to be a jammed floor mat was really a linkage or internal problem. The external linkage has now been lubricated, but appeared to be working perfectly before this lubrication. I suspect we are in for more excitement if we continue to drive the vehicle. As another Sienna owner pointed out, there was no recall issued for accelerator malfunction in our vehicles.