I am driving along when it feels like a harder-than-average shift occurs in the transmission. I press on the accelerator pedal and the engine just idles. There is no acceleration. The car coasts but doesn't stop. The engine is still connected to the transmission. As the car idles, it moves forward, but it will not accelerate until I "reboot" it. I pull to the side of the road, stop and shut-off the car. Then I restart the car and it runs fine. My mechanic is at a loss. Sometimes it happens a couple of times a week, sometimes several time a day, and at other times, the car runs fine for months without the problem. Anyone have any ideas? Thanks in advance...

Update from Jun 4, 2018: I took my car to Advanced Auto Parts. The folks there, connected the car to a computer that downloaded data from the engine. It reported that the "accelerator sensor" was faulty.

The sensor is built into the accelerator pedal assembly. The accelerator is connected to the engine by wire and not with a mechanical connection. This problem requires the entire accelerator pedal assembly to be replaced. the part is between $250.00 and $300.00 new, and $50.00 and $100.00 as a used part.

I bought a used part online for $50.00. I replaced it myself, (two screws and performing complex yoga to crawl and fit myself under the dash).

The problem recurred, but the longer I drove the car, the less often the problem occurred. The car's computer has adjusted to the new sensor and the car is driving like new, without any stalling. Let's see how it goes. I'll update you in a month or so.