Can it last a 4 hour drive?

A 91 with only 16k on it? Very low miles, have you have serviced it regularly and often cause it sits a lot? I would change out the oil and filter before the you do it just so you have fresh oil and they can check all the fluid levels then too. Other concerns would be all the rubber, belts, hoses, tires, age is not thier friend and they do deteriorate with time. If it checks out then it should be alright to go,there and back again.

Oil change with new oil filter use good oil and a good oil filter, check all fluids and top them off, check your tires and inflate to 36psi on all four tires. Toyota is a very dependable car,

You might have to fill up on gas before driving back.

That's a good ideal