I have a VZN130 surf that we have recently installed a 1uz into. We retained the A343h surf trans and swapped the bellhousing and torque converter onto the A343 from the lexus box. I've now had this problem twice while driving on the motorway where the whole truck starts to shudder through the driveline/engine very violently and feels like it is losing all drive as well. I can hear the engine revving when I push down on the gas, but with no effect. If I turn the overdrive off and on a couple of times, it seems to sort itself out, but it never lasts long enough (about 7-8 seconds) to really get my head around it. Has anyone got any thoughts on what it could be?