Geeze , Look at your manual and follow it.
Replace fluids and use synthetics where you can in , Power steering, Transmission , Motor oil, Differential, .Flush and ck brakes repair if necessary. Replace plugs and wires and cap use platinum plugs., Belts and timing belt water pump, hoses, Flush cooling system .Air filter. Oxygen sensor . Tires, tires balanced. Etc Etc.
With 84k the previous owner surely skipped most upcoming maintenance saving himself 1000 - 3500+ US, now its your problem if you want it to last.
Now at 84 is when alot of maintenance is necessary
For better mileage use synthetics in the trans, engine and differential. Mobil is best. It does lower friction. I gained 3-4 mpg here . Increasing tire pressure to the maximum allowed by the tire will reduce rolling resistance, although the ride may be harsh, you can lower it. I found the recommended 31-30 to mushy in steering and handling. I use 41 lb and gained 2 -3 mpg. New plugs, cap, wires, rotor, Air filter, can add 3-4 mpg.
Be sure timing is set and have car checked on a scope.
CV joints can go at 84
Batteries can go after 2-5 yrs
Thermostat? Radiator cap? Emissions system, Struts ?
I just did this and raised my 4 cil camry mpg. Avg last year of 20 - 28 to 26 -38 , And my plugs, cap, filter had only 15000.
If i was going to sell a car I would not maintain it, Get records.