I have an 05 RX 330 with 119000 miles. Car runs like a top except for this strange hesitation that occurs upon acceleration. I upped the octane to 93 (Costco only has 87 or 93) and it helps somewhat but the problem is still present. The hesitation occurs immediately upon acceleration from a stop and if I am accelerating slowly. If I accelerate a heavier I do not get the problem, but I drive a little on the cautious side. I also noticed it occurs when I'm rounding a curve or turning a corner.
I'm facing having to have the timing belt/water pump replaced but don't wont to do that if I am looking at a possible transmission problem. The car runs very well otherwise.

 

Tough to diagnose. Could be it needs a new set of spark plugs (due @120,000 miles). Could need a fuel system cleaning, throttle body cleaning, or all 3. There was a TSB on this as well the dealer does a software update to help sluggish acceleration I believe. I'd do the simple stuff first, run a couple bottles of Gumout Regaine High Milesge fuel system cleaner through two full tanks of premium, this helped me out with our 04.

 

Thank you so much for your input. I will try the gumout. I don't know what TSB is, could you explain that to me? Thank you.

 

Technical service bulletin. It's a step down from a recall (major liability if it goes unfixed), but something the auto maker needs to fix.

https://www.automd.com/tsb/lexus_m/rx330_mm/2005_y/

how long and how many miles have you had this strange hesitation? how long (seconds) is the hesitation when you try to accelerate.

I know for my 170k mile 2005 rx330, because it's drive by wire, there is always a slight hesitation before the acceleration kicks in.