i would change the battery and the alternator so any of the electrical powering problems are solved and its brand new..

 

my 07 monte did that as well and found out that my power steering pump and alternator was the culperet first step huck up a volt meter when your car is running it should read at least 14.4 volts no less than 13.8 volts if it reads less it is a alternator problem. how i found out my powerstering pump went bad is when i had it at the shop getting it fixed they put it on the rack rased it seen it before they tutched any thing and said it was a good thing i was heare and they had every thing to fix every thing to fix my problems. the low idel is a good thing. but when stopping and wanting to shut off changeall fileters do maintenence and go from there.it also sounds like a bad fuil filter or a bad plug do the cheapest things first. plugs wires filters oils and if it still does the low idel and want to shut off go after the alternator. what i am saying do the rutene stuff so youll have a peace of mind before youll spend money on the expenceve things