Yep - it's called a converter drain-back valve, or anti-drainback valve.
It's located on the transmission cooler line, near the radiator (passenger
side - look for the tranny cooler lines).  It should be fairly inexpensive
to change out, as it's just a one-way check valve.

Your friend could also just idle for a few seconds in neutral, which is also
a pretty good idea for the engine, too (12V engines should be allowed a
short warm-up cycle before driving off).  This will fill the converter up,
and eliminate the sluggishness.