weird stuff going on

Hi everyone,
Could someone please tell me how to replace the fuel filter on my 1997 ford escort? Also every so often when I have the brake on, and am at a red light, it feels like someone pushed down on the trunk of the car....what is this Help

feul filter is easy, just find it, it looks like an oil filter that comes off the gas tank. have a new one ready, and switch them. its a little crapmed, but buy a oil filter wrench (10 bucks any auto parts store) and use that to get it off, then screw the new one on