my buick is losing compression, I think. on 2003 Buick LeSabre

I took it and had a person put it on there machine, my computer reading showed losing compression on number 6. so I replaced that coil pack. and spark plugs & wires replaced. Ialso replaced the fuel filter. it's still bogging and not fixed. Please help me !

Asked by for the 2003 Buick LeSabre