Accelerator Sticking

I have a 1999 Honda Civic and I have noticed that sometimes when I push down significantly on the accelerator, it will stick in that position. Once I felt it release, but a few other times, I have had to hit the brakes to stop the acceleration. I took the car to the dealer and they said they could not find anything that would cause what I was describing. They did recommend a throttle body cleaning for just under $100, which I did have done. Unfortunately, this morning, I had it happen again. Any suggestions on what I should do?