My 95 thunderbird has problems shifting!!!

I Can't seem to figure out why my car has a delay when trying to shift into drive. I have to have a high RPM To get it into drive and when it hits drive it shifts really hard. Is there something that I can do to stop this problem. If anyone can help please give me all the ideas you can. Thanks

Is the fluid at the correct fill level? Are you checking it with the car idling in park or neutral? You won't get an accurate reading when the car isn't running.

I changed the transmission filter in the car so the fluid is as exact as you can get it. Is there anything else that could cause it?

Are you certain the filter was properly installed? Old seals can stick to the valve body and cause problems. How many miles had it been between transmission services? If you're unsure and your car has higher mileage it'd be a safe bet the tranny is on its way out. How did the fluid look? Were there a lot of particles/shavings stuck to the magnet in the tranny pan?