Stock truck. FP about a month ago ran 9. 5-10 psi at idle,pulled down to 8 psi(at the lowest) on hard acceleration. Now at idle its about 8 and goes down to about 7 and maybe a tad lower on hard acceleration. Fuel filter is a 5 micron baldwin,hasnt been changed recently,got like 2-3k on this filter 15k on truck. It has been colder here lately and my truck also sits for longer now than before(not my DD). What would cause this drop in FP?Filled up at same station as usual,truck runs fine,starts fine,not other issues besides a bit more white smoke on cold start,also another ? since the truck has never been in this cold of weather before. Avg. temp now is 30 with nighttime temps in the teens.