2000 lexus es300 runs smooth when cold but when engine gets to operations tempurature runs a little ruff and when stepping on the accelerator the car will accelerate then intermittently it will stop accelerating and if you hold the peddle in the same position it will all of the sudden buck and then continue to accelerate but if you feather the gas peddle you can get it to accelerate again without the bucking if you do it just right.

SOURCE: Bucking on Hard Acceleration

You best bet would be to look for the vacuum diagram and just take a day to make sure all of the lines to the engine and tranny are all correct. If its not it and while bucking the car feels like its going to turn off on you then it maybe a fuel delivery problem.

SOURCE: cruising at 2000 rpm's -

could be your throttle postioning sensor. short terms TPS

Jeremy W.

• 5332 Answers
• Posted on Feb 24, 2012

SOURCE: Have I ruined my engine?

check the signal on that wire with a lab scope. You should see a clear and definite est signal from the PCM. The wire should be ohm checked from the PCM to the module. If the code is setting as fast as you are clearing it than it should be pretty easy to figure out what is going on.

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SOURCE: Bucks on acceleration at 2300 rpm

It could be a single ploblem or a combination of the fuel system the engine could be starving for fuel or air or the timing is not set correctly. The transmission may need some adjustment.

SOURCE: 2006 Infiniti FX35 "bucking" when accelerating

It sounds like you could have a fuel injection problem, or a fuel system problem. Sounds like too much fuel is being fed into the motor too quickly. Unless you are very mechanically minded I think this may be a problem to be fixed by a mechanic.