Driving the other day and I was in bad traffic, so I put it in neutral so I wouldn't have to hold the brake down and I forgot it was in neutral, so I hit the gas and looked down than put it in gear than my car wouldn't idle after that, it keeps puttering, and won't stay any higher than 500 rpm's. When I press the gas to go anywhere it begins to stall and shut down. Any ideas. I will repair just need a clue on what I need to replace, and whether or not its worth fixing.

Propably when u pressed on the Gas and put it in Gear , the engine start running rich giving out all the obnoxious gases into the catalytic converter. Check the Converter and the Oxygen sensor switch is they are fine. Actually it should have brought the service engine light soon. But better late than never!