Evian do you mean that the engine will not rev but the engine is ticking over when you first start the car but when you restart it the engine will rev as normal ?. What car is it ?.
If it has a fly by wire throttle ( no throttle cable, the throttle is operated by an electronic signal from the pedal to the fuel inlet ) then it sounds like there is a problem with the signal being sent or received.
Try disconnecting the car battery for 20 mins and the reconnect it, this will reset the ECU and if you are lucky and it's just a glitch reset the throttle signal, if not then you may need a new throttle pedal but the only way to know this is to have the car plugged in ( to a computer ) and get the fault code from it.
The smell, I have no idea ( unless it's something burning / burned out ).