Howdy all. First time here.

I have a 06 pathfinder. My issue:
Lacking a little on power during the winter months, not bad though. Problem arises when ambient temp outside reaches 85 degrees or above. Car starts chugging, bucking and stalling, not wanting to start and so on. Has a bit of a fuel smell, occasional back pop. no codes. My kid said he spotted a little grayish to black smoke when I fired it up today. Did a fuel pressure test. Started at 47 and slowly dropped to about 45 (although the outside temp had dropped a bit by the time I did the test) I'm guessing the drop would be much more significant if it were hot out.

At any rate, its been suggested the regulators (dampeners) are bad. Any thoughts or ideas?

At idle, Nissan's spec for the fuel pressure test should be at 51psi. I have to assume, since you said it slowly dropped, that the engine was not running when you did this test. If it was running, a drop in pressure, even slowly, is not a good thing, especially when you were already measuring a pressure below where it should be. In either instance of how you did the test, without much else to go on, I could only guess that the fuel filter may be clogged. These integrated fuel level sensor/fuel pump/fuel filter assemblies buried inside the fuel tank are a pain in the wallet since there does not appear to be a separate part number for the filter that I could find.

Fuel pump was changed shortly before I bought it. was a running test.... unfortunately. I ordered the dampeners, they'll be in next week. If it improves my situation, I will definitely post here.