Car downshifts on its own???

My buddy has a 94 Camaro Z28 with the 4L60E tranny and he said it has started to act strange. Out of the blue, while he is driving down the road, it will down shift and speed up as though he floored it for a few seconds and then it will go back to normal. He said he did not push any harder on the throttle pedal when it did this. It does it one or more times in a row and the last time it happened it did it five times in a row and then died. I believe it started back up after this happened but it is a big problem. He says someone told him to change the throttle position sensor.

Any ideas?

Anyone else ever had this happen to them? What was the fix?

Thanks!

Jeff