last night i drove about 88 miles to the shore...when i was headed back i stopped ar Buger King and smoke started coming out of my hood so i tuned off the car poped the hood and let it sit there for a few...and mind you my car has misfired the week before so i took it back to the dealer and he restarted the comp...when i pull out of Burger King i notice that my RPM starts at 2...i aint think much of it...then i come across a red light so i put the car in nuetral i notice my revs move up and down by themself not alot but like about 1 rpm up and down and my car makes this droning noise...idk what the problem is....can someone give me professional help...