Car jerks while stopping and takeoff - LS 400 Lexus Cars & Trucks

Sounds like a misfire. But honestly it could be anything. If the check engine light is on that could point you in the right direction

If you have a carbeurator instead of fuel injection, the carb float may be bad. At fast stops or takeoffs, it stops the fuel supply. You ned to replace it and its usually not to hard unless you have to remove the holr carb to get at it.

I would check the spark plugs and wires or coil packs. Sounds like the ignition system is arcing.

I had a "what I call a clunk" in the drive train somewhere(mine is an auto) when I moved off from traffic lights/stop sign etc, had Kia mechanics spend lots of time on my car with no positive result. I found on a forum that another sorento owner had this problem which is, the tail shaft slipper spline gets dry and has a very small amount of play. There is a grease nipple to this spline, however this gets grease into part of the spline only. The only way to grease the spline properly is to remove the tail-shaft from the vehicle, clean out the both halves of the spline, grease well by hand and push back together, refit to vehicle. NOTES- when you push the splines back together any excess grease will bleed out of a small hole in the back of the front half of the tail-shaft in the universal joint area, this is normal.Also make sure you mark both halves of the tail-shaft before you slip the splines apart. I have done this twice now at about 30000km intivals (when I felt the clunk again as grease will eventually squash out) I use neverseize lube. Regarding the shudder on takeoff, haven't had that problem and not sure what it could be. Hope the above helps.

replace coil pack &wires

An automobile's ignition system may work fine while idling but fail during acceleration. Problem areas to be inspected include the spark plugs, spark plug wires and vacuum hoses. Car owners should look for spark plugs that are covered in oil or sediment or damaged, spark plug wires that have damaged insulation, and vacuum hoses that are unplugged or leaking. Fuel Problems

• The use of a fuel additive that contains both fuel injector cleaner and water remover can fix minor problems due to water in the gas and fuel injector clogs. A fuel pressure gauge can also be used to test the injection system to assure proper pressure.
  

While most acceleration problems are likely caused by problems with the plugs, wires or fuel, a variety of sensors and other components can cause similar problems. a bad tps ( throttle position sensor ) will cause causes transmission shift issues, bucking, jerking, idle surging, engine cutoff, hesitation on takeoff, and surging while going down highway.
good-day ! check and or clean maf sensor if need be. you can by the maf sensor cleaner at most auto parts stores.

The rear brakes may have some oil on them which will cause sticking/grabbing braking. Usually from leaking brake cylinders or calipers/wheel bearing seals. Pull each wheel and check. Another problem could be a bad 'U' joint at either end of the driveline. Make sure the emergency/parking brake is fully released. It's possible that a rear axle bearing is going out, but they will make a rough sound when moving. Make sure that the spring mounts are tight. Check the oil level in the differential. Shift from forward to reverse several times to see if this reoccurs each time. Get someone to watch and listen while you do this. Hope this helps!

all of the shifting solenoids are in side the tranny, by the sounds of if you might be able to try a service on the tranny, new filter and fluid might help alot. try that first before spending alot of money.

i would check and change air and fuel filters first.

it sounds like it may be out of time and in the case you need to replace timing belt and pulleys and get retimed