2007 LEXUS ES350 User Comment / Complaint

My car developed the flare/slip (1000 rmp gap) cold start first shift from 2/3 gear. it happened 2-3 times out of 7 days i sent the car to dealer, they keep telling me that they were not able to duplicate or verify the problem, i video tape the problem show it to the dealer however they told me that they have to duplicate the problem first in order to start to repair. after i pick up the car back from the dealer for the first time the flare/slip (1000 rmp gap) happened again, it happened 3-4 times out of 7 days, i sent the car back to dealer to check the problem. again they said that they were not able to duplicate or verify the problem.