No power when going up hills, HELP!

[Neal]

I have no power when going up hills. I'll be doing 75mph and then next thing I know I'll have it floored and I'm loosing speed down to 60 or so.

I just had the cat check and everything is fine there.

Check engline light is on and is pushing out codes P0171 and P0174.

Any help would be great.

1998 Ford Expedition 4x4 5.4L V8

 

[ELVATO]

Hmmm

P0171 - System lean in bank 1
P0174 - System lean in bank 2

You're getting too much air in, or not enough fuel. When's the last time you changed your fuel filter? Do you have any mods to the air intake?

 

[Neal]

Completely stock vehicle.

Fuel filter was changed 2 yrs ago I think? Maybe 15k miles ago. I didn't think about changing that, think it's due?

And from what I've read those codes together could suspect fuel pressure/condition or MAF Sensor.

 

[JUST4FUN]

Check the PCV system the valve is located in the passenger side valve cover,check the hose/plastic line all the way to the throttel body for any cracking. Clean the mass air flow sensor located in the air cleaner with brake cleaner or throttel body cleaner there are two very fine wires in thier. any vacuume leaks will give those codes

 

[Neal]

I replaced that plastic line about a year ago since it was cracking out, took me forever to find it. I checked it again and it appears to be good.

I'll clean the MAS and report back.