After replacing spark plugs why does it feel like my car is going to die at a stop

What is your question?

I recently had my check engine light flash, looked into the problem realize I had a misfire and replace my spark plugs. Now on occasion when stopped at a stop sign or light it feels like my car is going to die, shut off completely, but then catches its self and "reeves" like normal. My question is any idea what it could be and/or should I not be worried ?