Grateful if anyone can help me with this problem. Have a 2003 Verada, 3.5L,V6. Done 160,000 km. Recently, had to jump start the car. Since then the car jerks when speed reaches 60, 70 and 80 km/hr as if it's pushing back or the gears aren't changing smoothly. Had transmission serviced but no improvement. What could possibly be causing the problem?

I had a similar problem in my TJ and the symptoms were greatly reduced by replacing the RH engine mount. I'd recommend inspecting (or having someone inspect) the condition of yours before shelling out for a new one, however, as it could be something different entirely.

Thanks for the advice, ammerty. The push-back jerk happens at precise speeds, so it may be related to the engine performance rather than the mount. Otherwise it would jerk randomly.

You did make mention of jump starting the car. This would cause the transmission computer to "forget" its shifting pattern. I'd suggest disconnecting the battery, and reconnecting it again after 30 seconds. This will allow it to relearn how to shift smoothly again. I have encountered this with my own car. I'll post up the relearn procedure below.

http://i1190.photobucket.com/albums/z455/MYKHVERADA/Transreset.jpg