slight engine miss,shaking and rpm drop
 

guys i need your input,my 1992 ls400 was running perfectly then came a slight miss while driving from nowhere.It is past due for a timing belt maintance plus with the 216,000 miles it still have the original spark plug wires.My check engine light don't work it is just a slight miss you can hear it out of both exhaust pipes.Thank you for input!!

You've probably answered your own question,replace the wires and plugs and then go from there.
If you can hear it from both cylinder banks thru the exhaust pipes there could a problem with the rotor arms and/or distributor caps.
The drivers side coil can break down although this gives a 4 cylinder misfire.

+1, check the obvious ignition system. Original wires...you can do a resistance check but more than likely, they are due for replacement. With all that coming off, just as easy to swap the plugs. Rotors and cap have good longevity but since you are doing those others, just as easy since you are already there.

Let us know.