transmission jolting my ride, what gives? Options

[ArizonaRed]

Hey my car just recently started doing this: Its an automatic and when i start it up in park i usually let it sit for about five minutes to let the engine warm up. At first my rpms are at 1500 then they go to 1000 then i shift into reverse and then drive and im off. Now it sits at 16-1700 but still goes down to 1000, then i shift and the car jolts back or foreward. Also whenever the car acts this way, when i sit at a light it sits at 500rpm not my 800-1000 like normal. What is wrong with it? I just got the trans fluid replaced 4 months ago. I know my old honda jerked around if it wasnt warmed up but thats because it was at like 2500rpm, not in this case.