Intermittent rich condition P0172

[flusterated]

Hello all. I have a 2000 Explorer 4.0 V6 that has an intermittent condition. The code from Autozone is P0172. Usually when the engine is cold (but not always) the engine will run rough, especially when the RPM's are low and the car is cruising around 40-50 MPH. During acceleration and after the subsequent downshift, the "roughness" will subside. This also happens when accelerating from a stop. I have replaced the MAF, Coil Pack, and the O2 Sensor (behind the catalytic converter). The code says that a Bank 1 Rich condition exists and the culprits might be:
1-Misfire
2-Defective O2 Sensor
3-Fuel Injector problem.

My problem is that I only need the truck for about 1 more month and I have a few trips to make with the family. So i need the truck to be reliable but I cant afford new injectors.
My question is since it's not always happening what could be the culprit? I have on occasion driven 2-3 days without any issues. Other times it happens all day, but happens mostly during the first (cold) start of the day. If anyone has any helpful tips, i would greatly appreciate it. Thank you.

 

[yankups]

I'm not sure about your problem, I have a '99 and I kept getting that P0172 Bank 1 Too Rich, but mine stayed on. It shook real bad and had a rough sounding idle & sometimes it wont start. What was wierd was that if I could get a spark out of my battery it would start so you could just touch the jumper cable to the post & if it sparked you could try & the truck started by itself without anyone jumping it, I was replacing the neg battery cable all the way from battery down to starter after finishing, i tested & looked under to make sure everything was good & I noticed my exhaust pipe leaking, where the U bracket holds both pipes and the downstream oxygen sensors sit above on the pipes. I took to a muffler shop & they cleaned & welded the bracket on both (not just the one leaking) & my code has not returned my check engine light has not come back on. I don't know much about cars, I'm learning, but everyone I've talked to seems to think that the leak on my exhaust pipe below the downstream oxy sensor had nothing to do with my P0172 running too rich code. I think it does being that I had that part welded about 1 month ago & this is my daily transportation. Now I still have an issue with the not starting for some reason but my running too rich code is gone, this may not help you but you can try looking for some kind of a leak somewhere