My car started sputtering about a month ago but no engine lights or indication of what the issue is. I also noticed that when I'm completely stopped with my foot on the brake the car seems to rev and lurch forward with a thump. It hasn't actually lurched forward because I've had my foot firmly on the brake but it shouldn't be doing that. I have no idea what the issue is when I'm driving, the engine is humming along and then goes putt putt and then back to normal. It does this off and on with no regularity. It also does it no matter what speed or how full or empty the gas tank is.