Solenoid.........not a sensor.
Yes, if you take it out of gear and engine doesn't stall then TCC(torque converter clutch) solenoid is the problem.
remove the 3 wire connector on transmission
Inside the transmission side of connector you will see 3 connections inside, Center, left and right
Using an ohm meter, put probe on Center connector and the other probe on Right connection, it should read between 20-30 ohms
Leave probe on Center connector and put other probe on Left connector, should read 20-30 ohms
The two solenoids are inside the transmission but can be accessed with pan off.
You may want to get a quote from a transmission shop to change TCC solenoid, or have them test solenoids and quote a price to repair.
TCC Solenoid could be fine and problem is in transmission passage.
Automatics work using high pressure fluids in passages, that is why they look so complicated, and they are in a way, like looking at an electronic circuit board, but there are certain things that happen with each model of transmission, blown gasket in one section, blocked passage, bad solenoid, trans shop will know what to look for on an A4LD.