1995 Dodge Dakota Low fuel problems and engine temp issue

My 95 dakota starts to buck and lose power when I get below 5 gallons of gas (20 gal tank). Also just prior to that point my gas gauge will read half a tank and drop to a quarter tank all at once. I am thinking fuel pump issue or filter problem. My truck has an in tank assembly and anyone ive asked tells me I have to replace the whole assembly ($2-300) to fix any of the components. I cant find a rebuild for my specific truck. Is this likely the issue and is there any info on parts?

On another note I live in extremely cold climate. My truck temperature takes forever to warm up even at moderately cold temperatures and it seems to be the case regardless of coolant mix %? Im not sure what all the factors are in getting my engine temperature up. Any ideas?