94 mustang cobra fuel pump issues

I just recently had my factory fuel pump go out. I replaced it with one from advance. It cranks and runs fine. Then once I got down to half a tank it sputters likes its running out of gas I know my car has a 15.8 gallon gas tank I coast to a gas station and fill it up and it only takes 8 gallons to fill up. So I'm assuming I didn't put my fuel pump back in tight. I resituate the fuel pump in the tank I realized it wasn't in the lowest pocket directly below the opening for the fuel pump. I drive it again get down to a 1/4 this time and it does the same thing. I'm thinking I either didn't put my fuel pump sock on in the right directon. Or my gas tank has magically grown a hidden pocket. I used to get like 350 to the tank before I get near E now I'm getting like high 200's and everytime it starts running low I fill it up and it only takes 11 gallons. So that means my fuel pump isn't getting to like 4 gallons

- I didn't bend the hangar at all
- I know I have the right fuel pump its the exact same size as the old one and I cross referenced the part numbers
- I used to be able to ride this car down to E and get about 320-350 miles to the tank and now I get 240-270 miles to a tank right at a 1/4 tank and it sputters like its fuel cutting when I stomp it or go up a hill
- it only acts up when I'm at a 1/4 tank
- I did put the fuel sock back on

Is the anything special I missed? Like which direction should the sock be pointing? Because I totally didn't pay attention to that upon removal

The fuel pump in at he lowest point in the tank I looked down in it with a flashlight.

Any ideals?

The clamps are tight and I put the old sock back on. It had like a small 1/8 inch tear in it if that matters. And the hose I used was brand new it came in the box with the new fuel pump. I'm not sure what direction I put the sock in honestly its been like a month and a half. I heard there's a baffle down in the tank? Maybe I put it in wrong and it blocking the baffle?