My maxima has recently been having two distinct problems.

1.  This summer it started making noises while accelerating, the noise
is worse when the weather is warmer outside.  In fact if it's cool
enough out, the noise is non-existant.  What could this be?

2.  Last week it started having difficulty shifting from park into gear
when the car was first started.  If we let it warm up for a while it
will normally engage after a few tries.  We took it into the mechanic
today and they told us the solenoid had gone bad and that with this
year of vehicle they would have to replace the whole shift assembly,
which would cost around $500.  Do we really need to replace the whole
assembly or can something else be done?

Thanks!