To me it sounds like a line training flight gone wrong? Maybe an inexperience 737 pilot at the controls disconnecting Automatics (A/P and A/T) to make a manual landing then becoming so overwhelmed with the situation that they inadvertantly enter a stall due low speed/insufficuent thrust.
The reason why i suspect training flight is because of the storys of there being 3 pilots in the cockpit (maybe 1 was a safety pilot)
If this was the case it would re enforce the importance of leaving the A/T in arm as opposed to off during manual flight.. at least then you would have underspeed protection.