vacuum leak on 420a

[RapidKiller1392]

I have a 95 rs non turbo an I pulled codes the ignition, on off on off on. An it gave me codes 12, 51, and 55. 12 is that the battery was disconnected in the last 50 cycles, 55 is the end of the codes and 51 is system running to lean. My question is about 51, I know that if theres a leak the o2 sensors would pick it up as running to lean an compensate by running it richer. So what I wanna know is where I should start looking for the leak loke where is the vacuum hose an how do I know if its the one that is leaking

 

[EAKEREAK]

Check your egr and the hoses check your throttle body. Check the plastic hose from the egr because it'll melt from the heat

Try to spray some carb cleaner and see if your idle changes