2000 Lx470 Throttle/accelerator Shutdown Problem

[auscple]

Hi, I am a new memmber of the owners club living in Panama and would like to introduce myself and ask for any advice on a problem I frequently experience with my 2000 LX 470. The problem is that for no apparent reason the accelleration suddenly drops off (by pushing the throttle pedel right to the floor I can still maintain some momentum) but the engine must switched off and restarted before the accelleration will resume to normal. Has anyone else experienced this problem? ,,, the Lexus service center down here can not identify the problem at all.,,,, thanks in advance for any advice.