Please Help? At this point I don't know what to do.

Playing around with a car doing this can cost you a lot more than the small parts you've already bought. That misfire is sending raw gas into the exhaust and over a short time, it will damage O2 sensors and destroy the catalytic converters. When an engine with fuel injection has to be given gas to keep running, that's most often a sign that the Idle Air Control Valve (IAC) is defective or dirty. Or it might be the Engine Coolant Temperature Sensor or, if equipped, an Intake Air Temperature Sensor. All you really needed was a better mechanic.

Vacuum leak. When the engine revvs like that it's a vacuum leak or a bad IAC. Is your check engine light or service engine soon light on? If so scan the computer for trouble codes and go from there. For the misfire, do a compression test. You could have a burned valve or bad rings. A compression test will tell you. Hope that helps! Jim