P0303 is a #3 cylinder misfire.
P0174 is system too lean (bank 2)
P0171 is system too lean (bank 1)
Probably a vacuum leak coming from the o-rings in the intake manifold, the techs call them "clam shells
" pretty common failure, check for any tsbs, check for a vacuum leak there first
they seem unrelated as a misfire wont cause a lean mixture in BOTH banks at the same time.
Probaly the lean mixture is an old code or the previous code, and the misfire is what happened last night.
Lean mixtures cause really hot exhaust too.
Fixing it yourself is probably a waste of money, the dealer can troubleshoot this easier and also get a "real-time" look at what happened from the ECMr in their shop.
Dont you love 1996 and newer cars??