coolant leak

What is your question?

97 Cavalier. 160,000 miles roughly. Oils good, no weird smells, and I don't drive much, very gentle use. Yet it breaks a lot. At first, classic overheat, the antifreeze smell, etc. Took to a mechanic who found a hose wasn't on quite right, fixed it. He also pressure tested it. It passed. A week or so later, idling for a while at stop, terrible burning scent, very sudden, car overheated bad, I pulled over and stopped. Cooled down. Checked coolant tank later that day, it was empty. Brought to different mechanic. Pressure test again. Passed. Plugged it in and ran for hours at idle, cooling fans were good and it never overheat. It got close but the fans would turn on and it would be fine. Figured it was a freak overheat that caused the coolant to blow the tank. Ok. Exactly a week later, and I haven't used it in three days, it is out of coolant again. IT didn't overheat and ran like a dream since last mechanic but obviously something is wrong. Going to refill & run for leaks, ideas?

What makes this problem better or worse?

Not even sure now, but idling did have the most overheats

How long has your 1997 Chevrolet Cavalier had this problem?

About 2-3 weeks