Auto trans disengages when pressing gas pedal at mid speed

From your description the trans is falling into nuetral during kickdown .

Can be caused by low on fluid
a sticky valve or sticky solenoid in the valve body
loss of signal ecm
mechanical failure
here are the fixes for some of the known issues
http://www.transgo.com/products.php...d=264&countdisplay=1&start=0&addcountview=Yes

A free road test at a transmission shop might be the way to go

 

You'er not a two footed automatic driver are you? Stepping on the brake will disengage the lockup.

 

PROBLEM SOLVED! Sorry I didn't update this before, but I want to get it out there in case it's helpful and hasn't been addressed yet. Evidently, a number of years ago Toyota had problems with the accelerators sticking. So they installed a break shut-off switch that would kill the power and disengage the accelerator when the brake pedal was pressed - even so slightly. My problem was being caused by me sometimes slightly touching the brake pedal while pressing on the gas pedal. It was finally diagnosed when a technician rode along with his laptop plugged into the pickup system. When I told him the symptom was happening, he saw the brake shut-off switch engage. I now make sure I keep my foot far to the right when pressing the gas pedal. So, it was user error. Go figure.

 

I experienced the same problem when wearing my POS Gander Mountain hunting boots. Boots were heavy and wide in the sole and I couldn't feel the accelerator. Would end up touching brake pedal and engine would throttle down.

Ending up modding the brake pedal by cutting off a half inch on right side. Perfect fit now. Threw out those POS boots.

The software update that they installed when they cut my gas petal sucks big time. Feels like a turbo lag coming off the brake to accelerate. Bastards did it without telling me. Had I known how it would drive after the update I would have refused the recall.