Mechanic Q: My car is jerking and lunging at low RPMs. What do I need to do??

It is a standard and I have had it for 5 years. It has never done this before. A few months ago, I put fuel injector cleaner in it, with no avail. I was thinking I may need a new speak plug because it almost seems as of I'm not firing off on all cylinders as well. Would you recommend getting the new spark plugs? What other issues could it be?