Car feels like it's going to stall

I have a 2001 Nissan Altima with 85,634 miles, four cyclinder. I have taken my car to 2 places and have received 2 different things wrong. Sometimes while sitting at a light, the car feels like its going to stall but it doesn't. It does not do it all the time, nor has there been a service engine light. It will do the chug, chug, chug, but never stalls, sometimes it's more noticeable than other times. The dealship changed the spark plugs thinking that was the problem, after that, it still did it. So they put it on the machine and they claim the intake gasket was leaking at the #4 cyclinder.
I now just took it to a second place for a second opinon and they told me it's the idle air control. Do you have any recommendations?