My Rover runs perfect all spring and summer but it seems when the temperature outside starts to drop for fall and winter I tend to get the p0171 and p0174. No air leaks, newer 02's.

My question is, if the Maf is on its way out could it work properly in warmer temperature but when it's colder outside the elements wouldn't get hot enough and throw the codes if it's on its way out.

 

I'm getting the exact same error codes with another one for Gear 4 Incorrect Ratio. Im ordering the actual electronic sensor part and will screw it on my old MAF and post back results, if it helps any

 

Have you checked the injector seals.

If you're sure there are no leaks in the rest of the intake side and haven't already changed these seals then that's where I'd start. They're a lot cheaper than a MAF, though not such an easy fix and probably overdue replacement anyway. If the MAF/IAT was faulty you might get P0102, P0103, P0112 or P0113, but as it's only P0171 and P0174 the MAF/IAT is likely OK.

 

If you have a scan tool with live data, check the readings for the coolant temp sensor and the intake air temp sensor. If one of them is stuck at a higher temp than the actual temp of the air or coolant, the computer may not be running the cold start functions properly.