Sometimes, when I’m sitting/idling, say, at a traffic light, my car shakes/vibrates; I can really feel it in my steering wheel but it seems to be the whole car. Turning the a/c off seems to make it better. If I put it in Neutral while at the light, the vibrating stops or lessens so that’s what I’ve been doing when it happens. Otherwise, the car is in good shape; I do regular maintenance and I’m pretty easy on cars, in general. Any help will be much appreciated.
Sounds like you may be experiencing an engine misfire. Is the check engine light on? Have the engine trouble codes pulled and post them below in the comments. This can be done for free at just about any local auto parts store. If the check engine light isn’t on you may need to continue driving it for a while until the like does come on. This allows the engines on board computer time to pinpoint the effected area.
What can be done now?
You could start by replacing the spark plugs and air filters which wouldn’t hurt anything and may be time to do so anyway. Another cause may be fuel related. If this has just started happening since your last fill up, you may want to switch to a different gas station and try a higher octane for a few fill ups. Your last fill up may have some bad gas and the higher octane should help bring up the octane level of any fuel that is left in your tank.