Trans troubles

1972 duster with a 318 in it automatic transmission. I know I probably need to take it to a transmission shop but I'd like to try a couple things first if I can to mabye save a couple. It does not want to shift out of 1st very well (also it just does not have any get up like I know it should) you have to bring the revs up and let off and then get back on it to shift and if I go to pass someone while driving I'll get on it and it feels like it slips into neutral or something so I will have to kind of baby it back into a gear. First time owning a car like this let alone working on one but it's fun and i love it but any ideas will be much appreciated

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