Had you change thermostat? Couple of my fleet need new thermostat every couple years of winter.
On my exp with fuel filter in my F350 diesel 7.3L. I notice little loose power and fuel mileage was 13
That when I bought. Replace fuel filter it was cover in brown goofy and STUNK too. Now it average 15 and seem running quieter or it just my image.
With that picture of fuel filter you show. I am worry about fuel pump most time they go bad when you replaced old fuel pump. For me I prefer replace them every 30K-50K miles if I drive highway alot.
On Diesel I do at 10K-15K on fuel filter.