My 2002 Chevy Impala 3.4L has a code that says that there's a faulty Fuel Level Sending Unit and the gauge doesn't work. My question is would it be easier to just replace the entire fuel pump with the sending unit already installed on it or is it easier to replace the fuel level sending unit by...

So I purchased a 2008 chevy impala with the 3.5 flex fuel engine. It developed a longer than normal crank time when first starting. It runs amazing after the initial start and has no problem until it sits for a bit. Tested the battery and it was weak so I replaced it to no avail. Anyways messing...