Hard shifting once car is turned on and running in high rpms

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Once you turn the car on and started driving it would run the Rpm's very high then do a big jerking motion, after that it would shift gears normally but at 55 mph would be going at 4000 rpms. The transmission was replaced under warranty 2 years ago. We have replaced the crank sensor and speed sensor, and time belt- still the problem remains $1,800.00 later. help!