Now mind you, I am no mechanic or genius. All I can tell you is that I had a similar problem with another car I own. Just about the same story. As I was driving down the road one day, all the digital gauges and lights came on, and then went completely out. About five minutes later, the car started acting real sluggish, then died going down the road. These became common for the next few days until I could bring it in to the shop. After the mechanic looked over the alternator, the fuel pump, fuel filter, wires,etc....He finally came across the freeze plug, which he said was spraying water from the block. The water was shorting out the ignition wires. This is what was causing the instrument cluster to go nuts and making the car die he said. He replaced it, and I didn't have this problem any more. This car was not a Lexus, but my old Cavalier Z24. I don't know if this will help, but I hope you figure it out before you have that baby. Good luck! :D