Accelerator Stuck problems of the 2011 Hyundai Elantra

While driving or stationary and pressing the gas pedal sometimes the car will suddenly and unpredictably increase in acceleration or rpms, respectively, way more than intended even after releasing the gas pedal. A couple points to note: 1) the car is a manual transmission and during the described episode if you press the clutch and put the car into neutral the rpms will suddenly jump to between 6000-8000 rpms where they will stay sometimes for a 1 minute before returning to normal; 2) during this unpredictable increase in acceleration or rpms (if while in neutral), the gas pedal feels stuck as though it does not return to its normal state; 3) while in gear and driving, taking foot off gas pedal does not realize a decrease in acceleration or rpms, rather the car continues to increase at a fast speed as though the car was being pulled; 4) turning the car off alone sometimes does not resolve the issue as upon next start of the engine the rpms will immediately jump to 6000-8000; 5) this issue occurs with and without the floormats; 6) the issue occurs most frequently at start up and often resolves itself after a couple dangerous and scary minutes of monitoring the acceleration and rpms in response your toggling of the gas pedal; 7) the issue was noticed initially at roughly 90,000 miles on the odometer and occurs about 3-5 times a month; 8) I live in san francisco, California.