2012 TRD acceleration pwr loss

Pwr loss at acceleration between 10-20 mph for 3/4 of second. Must be moving left or right making a merging into traffic; stop & go no problem. Slam accelerator to floor and when it kicks-in the eng speed starts up slowly until about 30 mph and then it really kicks-in speed. Happened lots of times and because no eng ck light dealer can do nothing. Factory rep says the same, no ck light no fix unless "they" can duplicate. They've had truck for 9 days and nothing to date. Believe it is a sensor on the transmission and not fuel. Why not fuel - I pull a boat and it has never missed a lick on hwy.