03 impala issues

03 impala bought 2 years ago and was fine
for the first year and now it's been a
guessing game for what's going on with it
been to 4 different mechanics and none can
tell us what's wrong here's our issues:
Starts fine on the first start but then it's
stutters when trying to start..have to put foot
on the gas pedal while turning the key to get
it to start most of the time and when that
happens we get a rich fuel smell inside the
car.
Stalls just randomly whenever under 30 to
40km so come to a intersection it'll stall and
gets arm strong steering.
Sometimes it doesn't wanna move when
putting foot on the gas and when it does go
it jerks....
Anyways just wanting to know some ideas
or of anyone is having same issues others
are.pointing us to the crankshaft position
sensor but just want to make sure is all.
Thanks for anything advice