2005 VW Jetta

My car will decelerate at random times. Outside temperature, speed of drive, etc have no influence of when it takes place. The deceleration only lasts about a minute but sometimes is as drastic as a 20 mile decrease in that time frame. Almost had an accident yesterday. Car shut off while idling but immediately turned back on. Have taken it to dealership and they cannot figure this out. This car was intended for my 16 year daughter this year but I cannot let her have it if this issue is not resolved. It’s not safe almost had an accident yesterday during the latest deceleration event. Anyone Please help! Thank you!

You might have it checked to see if it has a stored error code? Have you owned the car since new? When was the last time the plugs and wires been replaced? How about air and fuel filter replacements?