well, if its common it must be common due to poor maintenance before you got it, and him neglecting his.
I have a 92Ls with 190k, and never have that problem.
My coupe doesn't either.
Sounds to me like time for a tune up...both of you.
Spark plugs - NGK or Nippondenso
Use only premium fuel (hope u never use 87...if so, shame on you)
fuel filter
oil change
timing belt/water pump (if not done at 90k).
This is why I asked how many miles....need more data.
Now, if this engine has high miles and/or has been abused, it is possible those plugs have a) alot of carbon build up, or b) saturated in oil.
Need more info. holla back