I paid 3000usd to get it fixed as you know the lexus has a lot of computer parts, i talked to the shop they said it was a electrical problem (computer) they said if i replaced the cluster it would be fixed but that wasnt the case so now i have an extra cluster and the same problem. i talked to the owner of www.lexls.com and he said that he had the same problem and replacing the od sensor and the no.2 solenoid would be the solution i know that my solenoids are good but my o/d sensor is probably the colprut, it only shifts abnormal when the car reaches normal running tempature. so i beleive it would be the sensor is overheating or malfunctioning, the only problem is i dont know where exactly its located lexls.com said its located near the exhaust, and where do i buy a o/d sensor no one in auto parts knows and they look at me like im dumb when i ask them can i get a overdrive speed sensor for a 91 lexus ls400, probably because they are to busy ordering parts for dodges and chevys. lol