I have 03 Infiniti G 35 when leaving from at a stoplight the car will not go more than 2 to 3 mph I get to the side of the road turn it off for a few minutes turn it back on and it's fine but it's done this several times already what could this possibly be. Hey seems like the gas pedal gets really hard as well

 

If the gas pedal is hard to press it sounds like you found the malfunction. The pedal on this vehicle is nothing more than an "dimmer" switch like you would find in a house. There is no physical linkage connecting it to the throttle body (throttle by wire).

First thing I would suggest doing is check toake sure there isn't something physically wedged behind the pedal like your floor mats or trash that made it's way behind the pedal. If it's not something obvious like that get it OBD2 scanned to see if there's any hidden codes. Lastly, the cost of a diagnostic fee is usually more expensive than a replacement pedal switch, it can be troubleshooted and the steps are online in the factory service manual. Try pressing it with your HAND and not your foot, it should be smooth with just a little resistance. If it feels wrong or "crunchy" or extremely stiff I would replace the pedal switch if it were my vehicle and just omit the troubleshooting.

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