94 Cav, shakes at idle

There are a zillion posts about idling engines, but I can't find this one. My '94 Cav, 2.2, shakes at idle, shakes fairly hard. It does NOT start hard, run rough off idle, use too much gas, blow smoke, hesitate, overheat or anything else. My only clue is that the temp gauge says 160 degrees. It rarely gets to 190. T'stat is new, tested in hot water with lab thermometer. Engine has been flushed, new plugs. 134K miles. NO CODES stored in computer.