It could be the shocks/struts or something in the steering system...have it checked out.
There are several things which could be causing the car to stall out while driving. The most common and least difficult problem is that the spark plugs may need to be changed.
I believe that vehicle has a timing belt, it may have let go.
with a wrench.
This is just my own experience, but the 2001 Infiniti QX4 that I am currently driving is going pretty strong at over 235,000 miles. As you probably have guessed, many of those miles are highway, but that kind of endurance is nothing to sneeze at.
Probably the alternator.
probably forgot to take your parking brake all the way off, or it could be the switch for the parking brake
Water Pump or Thermostat. May have to change water pump to replace thermostat.
5w30
One issue with a 2001 Chevy Impala hard shifting could be the pressure control solenoid. The car may also need something as simple as more transmission fluid.
Obviously you have a fuel leak somewhere.
fuel pump might be going out