My 98 taurus has this codes what do i need to fix? p1518.p0174.p0

P0171 and p0174 are o2 sensors, There are 4 o2 sensors on a Taurus. 1 on each exhaust manifold, and 1 after each catalytic converter.
p1518 is vehicle speed, idle speed control----this means the idle air control needs fixed. you can take it off and clean carbon from it. do not push on end of air valve it will loose its adjustment. do not put in any liquid to clean, the best way is to clean end of valve with an old toothbrush or similar. also clean carbon from engine side where iac mounts. when clean put back on. you can use carb cleaner for end of valve, as for the 02 sensors, you have to find out which ones are bad first. or replace all thats up[ to you. you have to get a 02 sensor socket for 3/8 drive. then they just turn out. the best way to get them out is have the car warm.