Ford ranger fuel system trouble?

[Cody Pyron]

Hey yall I got a 1999 ford ranger 3.0 with 140000 miles. Truck ran great till about 10000 miles ago. Runs and idles fine until at 45-50mph it starts to sputter like its low on gas. I can get on the gas peddle and will accelerate after about a second or two. Runs good once over 55mph. P0171 has been coming up with P0174 at times. Ive replaced all plugs and wires, fuel filter, air filter, oil changed regularly, and replaced all the egr system and all vaccum lines. Any ideas? Thanks in advance!

 

[Old Man Dirt]

If you have a clean air intake system that uses an oiled air filter, you over oiled it and the MAF needs cleaned.
It could just be that the MAF need cleaned because of oil from the crankcase ventilation system.
You might want to look at some ranger forums to make sure that you clean it with out causing any damage.

 

[bandit_60]

it might be the fuel regulator on the fuel rail. run a pressure and volume test on the fuel pump.