This fluid exchange is a slow process and it works, just have to give it time so don't give up just yet. Find a mechanic who is willing to drop the pan, clean the screen and check the shift solenoid. These trannies are very robust and the LS400 guys have managed to save many with this simple procedure. If it is beyond these simple tasks, your expense is still minimal and you have a 50/50 chance.

 

If there's no check engine sign is lit, there's no problems with solenoids.
There can be sticky valves, and it's a known high mileage A650 (01-03) condition. The valve body is made of aluminium, and after hundreds thousands of miles, valves can start sticking in their tubes, due to physical cast metal wear. This condition will result in delayed shifts and overall strangeness of shifts.
But when you said, that it's sluggish to accelerate - it's a telltale sign of torque converter damage.
Usually it happens due to long time use of dirty fluid. It loses it's properties, then seals start degrading, and particles going all around the innards. They clog up valve body (and solenoid microfilters, BUT any failure of the solenoid to act upon valves - say computer commands Sol1 OPEN, but it senses that control valve did not move, due to say clogging - will light up your dash like a xmas tree after 4 attempts to move that valve), and start moving further, pick up clutch material and then onto the torque converter, which is complex and fragile dual turbine. Hard pieces can break off turbine's 'wings', they start doing more and more damage to turbine propellers... Say there's 50 'wings' on each shaft. The torque converter will still perform 'as normal' with about 10% of 'wings' destroyed/bent. After that - more and more energy loss between input and output shafts. It'll heat up - huge friction, pieces of wings to into everywhere, scratching, cutting etc - and do exponential damage. Pieces can even pierce tranny body and shoot out (one guy had this happen to his GM vehicle on the move, and i'm not even joking. car was totalled. he was shaken but alive).

So, with all that knowledge now, i'd look for a 'guy', who at least worked on 10 A651/A761 gearboxes.
If your culprit is just valve body - it can be replaced with tranny still in car and (amazingly) new valve body (which ships from toyota assembled - with all solenoids in place and all springs and checkballs in right places. basically a bolt on install) costs only about 700usd. FYI cost of just one solenoid is 150usd-ish, and there's at least 7 of them in valve body. So do the math.
But with 'sluggishness' condition it's unlikely. Just as an info, in moscow there's some reputable lexus-toyota specific tranny shops. And prices are like this: 1. valve body replacement job (client buys parts) is about 400-500usd; 2. full tranny rebuild (includes new valve body, all new innards, everything new, BUT the torque converter, which is remaned by them using special robot(!), +12m warranty) is about 3000usd and quite reasonable at it (to rebuild merc 220/221 or say beamer-7 tranny is 10k+usd even for earlier models).

Hope this info is useful...
I have many miles on the clock, and my tranny performs 4.5 out of 5. Considering mileage i'd say it's an ace in a hole from toyota. I pan drain/refill every 20kkms and i replace my filter (now just blow it clean with air) every 40kkms.

 

5 tranny flushes later and I'm still having the same problem, and now it revs up then kicks into gear at first start up. Once warmed up no slipping but still sluggish and delayed shifting

 

have you tried techron fuel system cleaner?


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Symptom I'm just noticing.. Once the car is warmed up its very sluggish at low rpms but does fine at high rpms. It's pretty quick to shift as well...

 

holy smokes, tons of great info in this thread, let us know how this works out..

 

Meh, your torque converter is slipping.

This isn't a valve body issue.

You are slowly bordering going from just being able to replace the TC to having to rebuild the complete tranny. The longer you faff around with fluid changes the sooner you're going to slip into the rebuild area.

Get it properly looked at by a transmission specialist and stop fannying around.

 

Yup, sounds like rebuild creeping closer and closer....