Car shuts down after driving on freeway for 1 hrs above 65mph then slowing down. on 1996 Lexus LS400

Excellent condition low mileage, always garaged parents car with all service done at dealer. After driving for an hour or so on freeways at over 65mph, then when traffic backs up and you need to slow to low rate of speed, car turns itself off. Also same situation when exiting freeway offramp, car unexpectly stalls to stop. Looses all power steering and braking even though car is still coasting, very dangerous for our new 18 year old driver to experience!

by in Aptos, CA on November 26, 2012
3 answers 3 comments
ANSWER by on November 26, 2012
Gosh...this is a VERY hard problem to VERIFY, DIAGNOSE, and CONFIRM...imagine having to drive an hour before a symptom appears! My guess is ...possibly fuel injection may be dirty since your scenario presents a sudden deceleration after a long time of steady driving.
COMMENT by on November 27, 2012
Car restarts right away and no issues exist after it restarts. I can predict now when it will die and can restart while I'm coasting (although my 18 year old just freaks out and brakes hard, then restarts) When car dies, all lights go on in dash as if you turned the car off. Once it restarts, there are no issues. I've had this in to the Lexus dealer for a two week time frame, they had their mechanic driving it home for an hour each night with it only repeating itself once. Now the problem has gotten much worse as it will do it nearly every time. I have read this issue on post and it says Lexus says, "no problems exist"
ANSWER by on November 27, 2012
After it stalls , does it re-start right away? Is the 'check engine' light on , BEFORE it's stalling? Need to bring to shop when symptoms are present , to be diagnosed- POSSIBLE idle air control circuit issue.
COMMENT by on November 27, 2012
Car restarts right away and no issues exist after it restarts. I can predict now when it will die and can restart while I'm coasting (although my 18 year old just freaks out and brakes hard, then restarts) When car dies, all lights go on in dash as if you turned the car off. Once it restarts, there are no issues. I've had this in to the Lexus dealer for a two week time frame, they had their mechanic driving it home for an hour each night with it only repeating itself once. Now the problem has gotten much worse as it will do it nearly every time. I have read this issue on post and it says Lexus says, "no problems exist"
ANSWER by on November 27, 2012
you need a diag this could also be a trans lock up solenoid issue. have all codes scanned and post so we can adv
COMMENT by on November 27, 2012
I like that thought , I didn't 'read' the question that way until I saw your answer. Back in the 90s I had several customers with GMs that were like that - initial drive of the day it would stall due to lock-up not disengaging , then after re-start it was fine the rest of the day. Of coarse back then , it was very common , that in itself made diag. a lot easier......... I like the way you think Greg...............never mind........