"I'll appreciate your input reference safe.

"I'll appreciate your input reference safe maintenance procedure for my 2009 Hyundai accent gasoline fuel system (pump, filter, other)."
Identified fuel filter inside gas tank (cover in trunk).
Replaced air filter and spark plugs. However, there is still a severe engine missing when air conditioner is on. Also, engine power has decreased considerably.
I need safe procedure details to replace fuel filter and trouble shoot the rest of the fuel system or other to correct engine missing and lack of power.