2002 Silverado 3500 with8.1 stalling than no shift

[Sapman]

Hi, I have a 2002 Silverado with the 8.1 motor. It recently started stalling abruptly. When I restart it, sometimes it operates fine, and sometimes it won't shift into any gear. If I shut it down and restart it, it will then shift normally. In searching this forum, people have recommended replacing the crank position sensor, so I had that done. Stall have the same problem. I would appreciate hearing from anyone that has experienced a similar problem and what the cause/solution might be. Thanks