My 98 v-6 auto, recently started shifting real hard. You can really notice it during braking, and downshifts between 4th and 3rd. Any idea on what it could be?

 

Try replacing the tranny fluid. use Dextron. If this didn't help go to a good transmission shop & get id diagnosed. I don't think it is anything major, probably the linr pressure is too high. However; you should fix it before it hurts itself.