I have a 2000 dodge ram 1500 that stalls when I put it in reverse and in drive but idles fine in park and in neutral. Had code PO 740 so I changed the torque converter clutch solenoid not the problem. Replace fluid filter gasket still did same thing. Reset the codes put in a new TPS and a neutral safety switch new torque converter and still the same problem when the rear is in the air, it doesn’t stall as fast as when it’s on the ground when put into gear, but slowly pressing the breaks it shutters and dies And also, when in neutral, the rear wheels are spinning as if underload

 

In neutral, it's just drag making the wheels spin..... You could probably stop them by hand, but, I wouldn't actually try that..... Brakes will make 'em stop, and the engine shouldn't stall.

Does the engine struggle more, the harder you step on the brakes when it is in gear and off the ground? When its on the ground, and you put it in gear, does it stall like you dumped the clutch in a manual trans???

If you unplug the 8 pin connector on the trans, start it up, and put it in gear, does it still stall?

 

From your description it sounds like the trans is dragging down the engine. What happens when you first put it in drive or reverse? The code is the pcm not seeing a rpm drop when it goes into lock up. That shouldn't effect idle unless lock up is engaged.
P0740 Torque Converter Clutch, No RPM Drop @ Lockup

 

yes the engine struggles more the harder I put on the brakes until it eventually shudders and dies. And whe on the ground it just instantly dies when you put it in gear. I will check and see if the connector being unplugged kills it or not.