2005 Kia Optima Timing on a 2005 Kia Optima

2005 Kia Optima 4 cyl Automatic 80,000 miles

I had the timing belt changed on my Kia a few weeks back. The car was misfiring, experiencing loss of power. When at a stop, the car would barely go when pressing the gas, and then it would "catch" and go. I had to bring it back 3 times, before they agreed to "satisfy my curiosity" and check the timing. Even though they were sure it wasn't the timing, it was off a tooth. Now, I'm having similar problems, except it happens when the car shifts into second or third. The RPMs seem to be higher than before. Is it possible that they did not adjust the timing properly again?