I don't know if this will help? I had a problem on my '82 that was air-intake related. The screw on my air filter cover would work itself loose and make a horrible howling/rattleing noise as RPM increased. Made me worry till I found out it was simple.
O2 sensors are reasonably cheap, but the Toyota ones are durable as hell. My '82 has over 200,000 on the last one. Runs like a champ
I would check connections such as mounts, clamps, etc.
Hope it helps.