I have a 91 300SE. It ran fine. Then yesterday just before I turned it off it started to idle roughly. This morning it wouldn't start. Starting fluid didn't help at all. It just cranks without firing. At noon, when it was hot it started. Runs well at speed but idles very roughly. Any idaa where to start?

I would start checking your spark plugs, they are cheap and very easy to replace. Also common for distributor cap and rotor button to cause problems. Also check your plug wires. That should be a good start and most likely fix your issue.