Hello,
I have a 2001 ford f150 with a 5.4. Its at about 125,000 miles. OK in the summer it runs fine but when it gets cold out it idles rough and sometimes itll quit at a stop light. The code comes back as lean on bank one and two. I changed the fuel filter,pvc valve, egr valve all the o2 sencers and the fuel pressure regulator. I cleaned the mass air flow sencer and the throtle body. I sprayed carb cleaner all around the intake manifold gasket and the vaccum lines and the idle doesnt change. I checked the fuel pressure and it was at 32 ideling and 40 on acceleration. I cant find what the pressure should be any where. I dont know what else to try. Would the fuel pump be going bad or the catalytic converter? Any help would be great. Tired of sticking money in to in and not gainning. thanks

 

I get the same thing on my 02 XLT. I suppose that there could be several reasons for this issue. But rough idle & stalling point toward a vacuum leak somewhere. On my 02, 4.2L the likely culprit is the plenum bolts. The rubber seal on them deteriorates & leaks.
Good luck.

 

Agree intake manifold and/or plenum o rings suck air when cold.

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Those are around the accepted values for fuel pressure. I just had this issue with my '99.. I was almost certain it was the fuel pump. tested the pressure, but it was ok. However, I knew the pump wasn't priming when I turned the key on, at least sometimes. Took it to the delearship to make sure it was the pump, before I pulled the bed off for nothing, and sure enough it was. Pulled the bed and replaced the fuel pump only (not the whole assembly) and it seems to be running well. It just threw another code, so I'll have that pulled in the morning to see if its the same two codes