rough running 5.o 99 mountaineer

[hammerfore]

I have a 99 5.0 moumtaineer that runs very rough if at all. It is throughing codes po171, po113, po122, pi504, and pi409. This is my sons car and he tells me it was running " OK " and just died. When he got it going again it was running rough and through these codes. He has an aftermarket air cleaner and it seems to run a little better when the air cleaner is removed. I am at a loss as where to start.

 

[CDW6212R]

Hello, welcome, and check the fuel pressure. It's becoming more common to find a low output of fuel, either from a weak pump or a slight leak in the rubber hoses at the pump(in the tank). You need about 60psi minimum at all times, the 99+ Fords should have that kind of constant pressure.

That P0171 code is a lean condition, which usually is fuel, or an excess of air from a vacuum leak. The V8 302's didn't have vacuum leaks typically, unless work was done to them and something didn't get sealed quite right.