Most 1999s have VVT. First, clear the codes. Then pull off the cam pos sensor and check for a light oil leak at the rear cam seal. Clean the CP sensor and put it back, before buying a replacement.
You can also check the timing by rotating the engine by hand and visually checking the cam marks. They need to be spot on the mark. Your next scheduled timing belt change is at 200K.

The oil should have been synthetic, but dealers cheat and use cheaper dino stuff. You might want to run a bottle of AutoRx to help clean things out. Make sure there is a Mann filter.

Replace the air filter with new, as well as the cabin air filter.

Replace those iridium plugs with copper! Copper lasts longer and the ignition is designed for copper plugs.

The screw that holds the kick panel needs to go through a metal clip. Make your own by folding over a quality metal tab and drill the correct size hole in the tab.

Klaus
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Common sense trumps a PhD