Yes, one of your ignition coils (you have 2) are bad on the -92 LS400. It's probably the one on the left hand side of the engine (ignition coil 1). See picture below for position of the ignition coils.
OEM part number:
Ignition coil with bracket & cord (easier to install)
- Ignition coil 1 (left), 1908050011
- Ignition coil 2 (right), 1909050010
Coil only, 9091902197
If you have the money for it I would recommend to change both ignition coils.