check for a vacuum leak, - i have an 07 RX and changed all the vacuum lines, and it made a difference for me, cheap and easy, lol
vacuum lines cost less than 5 bucks from super cheap, they have it in bulk, i got 3 meters of the smaller stuff (if you have cruise control it may cost more as the throttle body actuator runs on vacuum, think about double the amount) from memory it is mostly the 3 mm stuff, but i would check
also remove and clean the maf sensor - i use electrical contact cleaner,
clean the turbo control solenoid (lives near the air filter, all the vacuum lines go through it) - i use electrical contact cleaner, magic stuff
then there's the SCV that may need a clean/replacement, i haven't had to do one of those yet so i'm not too sure about how long it takes, or cost, but reading on the forum its a couple beer job, (it lives on the back of the vacuum pump) evidently cleaning in diesel is the way to go with this
if everything on the vacuum control side checks out then there's possibility that the egr is not blocked and possible stuck open (robbing exhaust to spin turbo up quickly) - if you haven't blanked this i highly recommend it, made a huge difference in throttle response to mine when i did it, - also look for exhaust leaks pre turbo while lookin at all this
another thing that may sound completely unrelated but i was surprised what it did to mine, was look at when the last time your fuel filter was changed, over time it blocks up and turns into a fuel line restrictor - mine got so bad that the engine would actually miss and throw fault codes under heavy acceleration due to fuel starvation
im sure there will be lots more advice on this as well
remember always try the simple easy stuff first, cause it usually doesn't cost alot of money