My car has 225,000 miles on it a Suzuki Aerio. It has ran fine all along. It just started having sessions of heavy vibration when idling. It does not do it when it is going only idling like at a stop light and only once in a while.
Check the engine and transmission mounts. If the mounts are okay, give it a really good major tune-up and then clean the fuel injectors ( you can also use techron if the budget does not permit for a dealer type of fuel injector cleaning). Clean the throttle valve and make sure the air cleaner is clean.