So bear with me hear this is kind of a long story. It all started back in November. I was planning on going on a wheeling trip that was 150 miles away. The truck had been sitting for a couple of weeks and I noticed that the front right tire was very low. I drove it to the discount store down the road to have it repaired. They said they couldn't repair it due to it being a 12.50 wide tire mounted on a 7.5 wide wheel. They said new policy won't let them touch it for safety reasons, even though they've been selling and installing that size tire on those wheels since 2005. They did offer to air it up for me. So I pulled around to their air check bay and the guy there said it was too low for the fancy machine to register and turn on. Tire was at 8psi. They tried for awhile to trick the machine but it wasn't having it. Finally I get fed up and head to the auto parts store. I go inside and buy a small air pump and a tire plug kit. I hook up the pump and let it run. While waiting, I start checking fluids. Engine oil was a little low, so I bought a quart and dumped it in. Tire was finally aired back up so went to leave. Started truck. It ran for a few seconds then died. Tried to start it several times and it would just stutter but never fully start. It was throwing lean codes, so I suspected a fuel issue. Checked all the fuses and they were good. I bypassed the fuel pump relay to see if that would help. Still nothing. Finally I gave up and had the wife come pick me up. I went back with a trailer and winched it onto the trailer and took it home. A week goes by before I decide to mess with it again. I try to start it and it starts right up. So I unload it off the trailer, and clear out the lean codes. I take it on a test drive and monitor the fuel trims. The fuel trims started out fine but after about 20 miles they started to indicate a lean condition, and the lean codes eventually returned. The infamous vacuum elbow had already been replaced a few years ago so I don't suspect that as an issue. I sprayed brake clean around the vacuum lines on the engine and couldn't hear any change in engine idle. I suspected maybe the fuel pump was finally going out, so I found a pump online for cheap and replaced it. I'm still getting lean codes. Truck is running great though and has plenty of power. I drove it for about four hours non stop the other day, and had jonissues with it not wanting to start. Just the lean codes. I'm half ass thinking that when I added the quart of oil to it, I might have overfilled it some and somehow some oil worked its way through the pcv system and got on the MAF. I haven't checked the MAF yet to see if it's dirty, but that will be my best step.

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2003 Ranger FX4 level II. 3" BL, 33x12.50 GT Radial Mud Claws, Custom front and rear bumpers with winch hookups, custom flatbed, with hi-lift, and full size spare mount, 12,000 lb winch mounted under bed, Electric fan, and of course a flowmaster.

If the oil was low, and you only added 1 quart, that's not the problem.

My wife has a 1999 Explorer Sport with the 4.0 SOHC & had the CEL on . I checked it for codes & it had l/s & r/s banks lean codes. After doing some research on the internet it turns out a bad DPFE sensor which controls the EGR valve could cause it if it is bad & the egr valve is letting to much air into the engine thus causing a lean condition. Here is a link to a you tube video about how to check it. After watching the video I checked the DPFE sensor in my wife's Explorer & it failed the test. I ordered a new on & installed it along with the 2 vacuum hoses from Rockauto & it has been good for over 2 weeks so far.

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2000 Ranger Extd Cab XLT, 4X4 Off Road, 4.0L, Auto, 8.8 - 4.10's, 01 grille & lights swap.
69 Mustang, modified 5.0, & 5spd.(project)
99 Explorer Sport, 4.0 SOHC, Auto, 8.8 - 4.10's, PW, PL, PM, Cruise, Tilt. (Wife's DD)
05 F-150 2WD Regular Cab. ( My DD)