If your Car's RPM are dropping suddenly and you press accelerator pedal but engine is not increasing RPM then most likely problem is with your accelerator pedal sensor. It can be confirmed with checking fault code with diagnostic tool available with mechanics, and if the code is P2121 then for sure the problem is with accelerator pedal sensor. Sometimes it also given check engine error light in dash.
REASON: This problem arises when carbon and dust particles accumulate inside sensor and it can not read its position. Usually when you go for car services, when the service guys blow air near pedals, the dust goes inside sensors problem starts arising.
SOLUTION: Simply you need to open the sensor and clean it with any cleaning spray, Contact Cleaner / throttle body cleaner etc. If the green color plastic bush in sensor is worn out, replace it when new one and the problem will be solved.
See this video for complete understanding : https://www.youtube.com/watch?v=y-eol67YdAk
