Why does my 1993 Ford Crown Vic barely move when I accelerate?

My crown Vic has been having this issue for a while now in that I can crank it, put it in gear and then have to floor it just to get it to move. I can hear the engine revving but this little old lady just keeps chugging along at her own pace.

Once she does get up to speed she ll hold speed just fine so in town driving is not as big a problem but she won't go fast. 0-20 in several blocks instead of a few feet. I had a friend suggest either the vaccum seal has unsealed or something like that OR the Cadillac Converter is causing me troubles. Any ideas?

If the engine revs with no problems the issue is probably with the transmission slipping badly.