Car wont start

Those are hydraulic lifters and they are not adjustable. They get noisy if they get gummed up from lack of oil or oil changes. If you have the 4.7 liter engine, they often have timing chain problems. I would get back to the guy who sold it and ask him what's going on. Hopefully it's not a mechanical problem inside the engine. Okay. You can also check for fault codes by turning the key from Off to On three times in five seconds (quickly). Stop at "On". Don't crank/start the engine. Watch your odometer readout for four digit codes. When the code(s) are done it will show "done". Google those numbers to see the problem if there is one stored.