A car shakes when stopped at lights but when you put on Neutral or accelerate it's OK why How much would cost to fix?

If this is a Ford Escort (aka Tracer) get the powertrain mounts neutralized, and if that doesn't work, just remember that Escorts are like that.

If not an Escort, suspect low idle speed, misfire at idle typical of poor fuel control, or damaged or soft powertrain mount.

== == low idle tune up out of balance engine bad tranny mount bad engine mount price varies by car and problem