What is wrong with your pool pump if circulation is not what it was before and it's very weak at startup and after a while it stops altogether but you still hear the pump running?

slow start is caused by your impeller being plugged or your start capacator going out,what kind of filter do you have sand,cartridge or DE?When was it last cleaned?Is there air in your pump basket?Are all your skimmer baskets clean?Is the body of the motor to hot to touch? Sounds like a bad motor.