98 3.8L with 156K miles, odd symptoms. Car starts and runs great but with Low Coolant light on. As she warms up, the Low Coolant light turns off and then operating temp goes higher than usual when you come to a stop, a little more than halfway up on the gauge and she starts to idle a little rough. Never overheats though. Revving the engine in neutral while stopped has no effect on the temp, but moving forward will get it to drop a little. Except if you get on the hiway and cruise at 70, then temp comes back up. Not sure if this is the T-stat, cooling fan or something else. Also not sure if the rough idle ties in to this or is due to the overdue plugs/wires change. Thoughts?