I bought 2000 Avalon with 279k miles car runs excellent any suggestions to keep

Just keep doing what the previous owner did!.. Keep engine serviced regularly... May be due for timing belt and 'components kit' unless you have a record that it's been replaced and at what mileage... Suggest having your mechanic take an overall look at it... *Keeping it maintained is the key* I've see seen 500k on em. Without any real problems... Toyota in general has proven to be a good reliable vehicle!