Transmission shudder?

You got it. It is likely shudder. If it has been 30K miles, a service job may correct the problem. There are additives out there like LubeGard red or Shudderfix that can help immensely. Make sure the trans is completely serviced including draining the torque converter and replacing the filter. If the torque converter is not drained, over half the dirty fluid will remain in the trans. This may be why you are having the problem now. There are cases where the converter is actually failing and, will require replacement of the converter. Try the complete service first. You should notice an immediate improvement. I do not recommend a "flush" on this trans because it can be completely drained as described above. A flush by nature does mix some old fluid with the new during the process which makes the complete drain preferable when possible as as is the case on this unit.

Could also be an ignition problem (plugs/wires). Although your discription sounds more like the torque convertor.

This problem has shown up with my 97 T-Bird on two occasions. Both times were cured by a trans flush and fluid change. No additives.

Frank

I had the same problem with my 94 CV. Draining the torque converter did the trick.

I had the trans fluid and filter changed on the first attempt to fix the problem. That helped a bit. After seeing a posting about the torque converte drain I had the garage change the fluid and filter and drain the torque convert. All was well after that.

Best of luck