[William Le Leslie]

2002 ram 1500 5.9 v8, put a new motor in it and had trans rebuilt, now when i start it up and let it idle for a minute and put it in reverse, it will either stall or die, only in reverse.. If I give it a little gas before I shift, it won't do it as bad.. And it doesn't do it every time.. Where should I start?

 

[ImperialCrown]

The engine/transmission assembly will tip to the right in Drive and tip to the left in Reverse. Make sure that all wiring harness connectors are securely plugged in, tied down and not rubbed through on any sharp edges that might ground out a wire and away from any hot exhaust parts that could burn through any plastic insulation and also ground a wire.
When the engine tips to the left, make sure that the right motor mount is not causing excessive movement. I've seen distributors hit the firewall from bad mounts.
The 46RE transmission may have internal ATF pressure leak that 'turns on' the lock-up torque converter when put in reverse. Worn front pumps and torque converters can do this. An ATF pressure gauge screwed into a TCC-apply port can see if this is happening. Electrically it may be staying off, but hydraulically may be coming on.
Any fault codes or have you tried any data recording with a scan tool to see what leads up to the point of stall?

 

[Muncle]

Did you ever get this fixed? Mine did the same thing. I had a cam/crankshaft sensor code come up the first thing I changed was the crankshaft position sensor.it didnt fix my problem but the stalling in reverse stopped. I would suggest changing it if its still stalling but it is like $60