My 96 ls 400 has about 140,000 miles and has been pretty good to me but one day the engine started surging from low to high and when shifted into gear wanted to take off like a bat outta hell, and when I had to stop it would be hard to keep it in one place, when i let off the brake it would go 0 to 100 all by itself, any info appreciated.

 

Check the throttle cable connected to throttle body. Maybe the cable got rusty and it's not moving smoothly. Spray some lubricant over throttle cable that is connected to the throttle body. Also check your car's gas pedal and make sure the cable attached to it is not stuck in one position.

 

If that don't help. The next thing you should check is your throttle position sensor. In google search type how to test Lexus ls400 throttle position sensor. Last but not the least also check your car's IACV valve. Make sure your car's IACV (Idle Air Control Valve) passages are clean and also clean the valve. Google search how to clean LS400 IACV.

 

Thanks for info