Why does my transmition jump when I first shift it into Drive?

Check to make sure the motor mounts and trany mounts are good. If there is excessive play, it will feel like that.

IF the RPM's are high (I didn't know) then that is what is most likely causing what you feel. Check for vacuum leaks and check the idle air control valve. If the check engine light is on, have the computer scanned to get trouble codes. Most parts stores will do it for free.

Just to add to this one most auto parts store dont read obd1 codes like your car has. There scanners usually only read obd2 codes. The most common reasons for high idles on that car are vacuum leaks. Inspect the hose running from the intake manifold to the pcv in the valve cover. They tend to get holes in them. Also on the back side of the throttle body injection inspect the vacuum hose elbows for holes leaking vacuum. Those are the two most common places for vacuum leaks and number 1 cause of high idles on that car. Let me know what you find.