Toyota Repair: 2004 Toyota Sienna AWD

Question
I have a 2004 Toyota Sienna AWD that has 120,000 miles on it. It is a 3.3 engine.  The check engine light came on and it had code 0333 knock sensors and P0037 oxygen sensor.  The description of the knock sensor was exactly what the van was doing it had hesitation when you would give it gas you could be going up hill and have it floored and would be slowly going then all of a sudden it would go.  This did not happen all the time.  A toyota mechanic replace the knock sensors both of them and they were toyota parts the oxygen sensor again toyota part it was on the Bank 1. and he also replace the wiring connection on the knock sensors.  I just knew it would fix it wrong...coming home I had the sluggish at some points and some points the rpms went higher but it was like it was not changing.  Mechanic is scratching his head and also I had to put in a brand new battery on the way home he said he had to jump it off twice and that could be affecting some things.  He also had me change the air filter.  Almost 1000 and this thing is not fixed and I am out of money.  He has no idea what to do becasue all the codes are clear.  It did the same thing with him when he drove it.  I hope you have a clue what is going on. I thought maybe the fuel filter like it was getting cut off and the air filter the way to best put it is like it is straving for something gas or air and all of a sudden it gets some...hope that makes sense.  Oh the fuel filter can not be changed becasue it is in the gas tank or something like that and it never needs changing.

Answer
Hello,
In most cases the knock sensors are not the problem and rarely are, the code can come up because there is another problem with the engine that causes the sensors to go out of their designed parameters and the light turns on. They do what they are supposed to and that is to detect engine knock or in some cases engine pinging and pre ignition caused by gas contamination, engine timing issues or a mechanical problem that sets up a vibration to trigger the light.
I don't have a definite or quick answer here, I can only make a few suggestions. You say there are no codes now but it still has a drivability issue.
A couple of suggestions,
have the fuel pressure tested under driving conditions
Have the timing belt checked
put some fuel injector cleaner/gas treatment in the tank and see if it helps
if it does you'll know it's fuel related
If the light turns back on let me know what codes you are getting