ejcrossl

I took my GS300 (145,000 miles) to the dealer because it was hesitating from stop. Give it gas, it does nothing, then jerks into acceleration. Hesitation amount varies. They told me my resonator had a hole it in so it was not getting enough air to accelerate. They plugged the hole, charged me for new hoses, reset the trans control unit and sent me off until the part came in. It was fine for about 1.5 weeks, but started to hesitate again. I told them this, but they just threw the new part in, reset the control unit again and told me to make sure I got 3 to 4 tanks of premium running through it.
It has been doing the same thing since I left there (on my 2nd tank, plus Techron injection cleaner). Yesterday was really bad, I didn't think it was going to move. Thought I heard a couple little "pops" before it accelerated.
Any ideas what could be causing this?
(They changed the transmission control unit for a hard shifting issue about 6-8 months ago, and had to change it again when an oxygen sensor went bad because the new part wouldn't work properly with the previously replaced unit)