Did you look at the sender when you pulled the fuel pump out? They get dirty and don't read right, or it could be in the connector or wiring.

 

It pays to be methodical in diagnosis rather than just throwing parts at a problem. Actually I guess you could say it "saves" to be methodical.

If you had the pump assembly out and now your fuel level readings have gone whacky, that pretty much points to the likely location of the cause.