Hello, I'm new to the forum...thank you in advance for any guidance. I have a 98 GS 400 with 319K on it. The engine runs so beautifully that at 300K, I was sure I'd get another 50-75K out of it, and purchased 90K Michelin tires!! But recently, I've had issues with starter, AC, and now a sudden loss of power (like it would not get into gear, while driving). Here's the quick history. Starter was dying, so I had it replaced. The day it got replaced, the AC stopped working -- blower was blowing fine, and up till then, no AC maintenance has been needed for years, but no cold air. Neither Lexus nor another Mechanic had an answer, other than to say the compressor was failing, and it was just a coincidence that it happened at the same time as the starter. Then, 5 days later, completely on its own, the AC came back on, blowing cold, no problem. Complete mystery there. So, I took the car on a vacation, and on the way back, while driving 65 mph on the freeway, I pressed the accelerator to take it up to 80...and nothing changed. No acceleration. I heard some light knocking...nothing powerful, but distinct. The car seemed to be engaged at about 65 mph. I did not attempt to brake...then within about half a mile, the car began to slow, and it seemed to be able to find no gear...couldn't speed up...as though it were in neutral. So I coasted off to the side of the road, and later go towed home. The car showed no signs of overheating...I check that guage frequently while driving, and there was no steam etc. On the side of the road, the car would start, but it would not stay on...that is to say it would rev, then turn itself off. All fluid levels are fine. As of today though, in my driveway, the car turns on as normal. You can press the accelerator down and get any rpm you want. The car will idle forward or reverse. I have NOT taken it out on the road though, and I have no idea whether it will disengage and then I'll have to be towed again. And here's one other item for you...this was the one and ONLY time ever that I have driven the car 5 hours straight with no break. I drive 6-8 hour trips regularly (on flat land, no hills), and I always take a break about every 90 minutes or so, two hours max. This one time I decided to drive all the way home with no stops -- so maybe that damaged something? I was driving steadly at about 65-70 miles per hour, from Atlanta to Jacksonville. Temperature was about 80 most of the day, maybe 83 when this event occurred. So - what are your thoughts? Fuel pump? Transmission? In case you're curious, I've had the car since 175K, and have done whatever maintenance was needed to keep it running, and have been very satisfied with it till this last month.

 

Vacuum leak?

 

Almost the exact same thing happened to me coming back from the beach a couple years ago. Car stalled but started fine the next day. It was my fuel pump. The dealer did a fuel pressure test and confirmed it.

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