My '91 Previa 220,000 happy traveling miles has begun running a bit rough when cold. I first thought it was bad gas (I live in Central America), but the problem has persisted after a tank of Premium fuel. My initial thought was spark plugs, wires, distributor cap and rotors. Then engine had a complete haul out and rebuild 25,000 short miles ago. Could these parts have faded out so soon?

if they were not installed correctly you can get all kindsa rattles and noises

One assumes they replaced spark plugs during overhaul, but can the same be said of ht leads and distributor, when was the fuel filter last replaced, your air filter should be replaced every 30000 miles but that also depends on your location, the more dust the earlier a replacement is advisable. But running rough when cold is a bit vague, best to check out simple electric's and fuel before assuming more dire causes.