Hah- welcome to the fold, my son
Carfax will usually only show dealership service- if a competent shade tree or small shop did it, it won't shop. If Billy Bob the jackarse did oil changes with a screwdriver and a hammer and an adjustable wrench, that won't show up either. Buying used is an act of trust in a complete stranger- best done with massive amounts of intel
I'd swap the plugs (STAY OEM! They work as well as anything else out there, and aren't $$), make sure they're gapped right, and check the plug wires. Take a spray bottle full of water, set it to a light mist. Spray it over the plug wires (not right on, but just over) with the engine RUNNING, and look for a light show. If you see arcing (you'll know if you have it!
), replace the wires as well- Mark W.