2005 Chevrolet Epica LT review from North America

I have had a 2005 Epica LT for almost 11 months. Just after a few months, while cruising along, the car was bucking and jerking at intervals for no apparent reason. Also, the shifting of the automatic transmission in the lower gears was so jerky and noisy that, at one point, I thought that the bottom had fallen out of the car. The dealership replaced the throttle and that did eliminate the bucking and jerking while criuising along, however, the jerky shift shock when the transmission was changing gears, did not improve. The engine light began to pop on intermittently and after a few more trips to the dealership, they determined that it was an O2 sensor. Unfortunately, the sensor had fused itself to the exhaust manifold so all of that had to be replaced. I had just a little over 2 weeks of blissful, smooth and jerk free driving and now the jerky shift shock, when the lower gears change, has started again. The dealership insists that the transmission is OK. Anyone having the same problem?

Aside from the annoying jerking when the lower gears shift, I like the ride of the car and find the seats extremely comfortable for someone with a bad back.