Ok, P2187 is a lean condition code, which simply means that there is more air in the fuel to air ratio than there should be. This can be due to unmetered air entering the throttle body or intake due to air leak at the air intake tube, vacuum hose or even intake manifold gasket. Or from too little fuel due to clogged/dirty injectors or weak fuel pressure.
The air intake tube, vacuum hoses and intake manifold should be checked for leaks and corrected as needed.
If ok, fuel pressure should be tested. If weak, then replace fuel pump
If no air leaks, fuel pressure good, then injectors should be cleaned of carbon buildup which will cause a lean condiiton.
As long as everything is tested properly, and no other problems found, then a fuel injection cleaning should resolve the P2187.
Cleaning injectors of carbon will also help increase/restore gas mileage as well as help it run smoother