Broken crank? Wow haha that seems so unlikely but I suppose anything is possible.

Did you get all new motor/tranny mounts for this car yet? What current fault codes do you have? Or is the light off?

 

It´s been a long time. My hopes for this car were already quite low... Theories of broken crankshaft, weird electrical gremlins, injectors and other things were all still in the air (My last try was installing a new Lexus transmission). I have been very busy with work and family lately so the GS400 was a project in the "freezer". Two weeks ago I met a technician who seemed very knowleadeable and eager to troubleshoot my car. With no expectations whatsoever I took the car to his shop. Three days later he sends me a text message.... "Your car is fixed, you can come pick it up"
I just replied OK, see you later this afternoon. I was very skeptical, and at the same time, very anxious to find out if it was true!
A few hours later I went to the shop.... the guy is the real deal! The engine spins smoothly as an electric motor!

I used to like this cars ride, seating position, brakes, sound system, torquey engine, etc. But the vibration kept me from going past 2500 RPM... it felt like it was going to blow up.
Now... its like getting to know this car all over again. It has a little over 55,000 miles, low mileage JDM engine and new transmission. This car is pure magic. Its quiet, very refined, and quick! Cruisiing at 80-100 MPH is effortless. I am in love.

Thanks to all of you who supported me with ideas. Ohh yeah, almost forgot! The culprit... ahhahahah. Incorrectly installed engine mounts. Incredible. Same mechanic who left a nut under the intake manifold creating a huge vaccum leak. The idea of hiring a hitman has crossed my mind....

P.S.: how do I edit the title of this thread to include the word "FIXED"?