I recently bought a 93 Cadillac Deville with 189XXX miles on it. It ran great. About 4 days ago it started acting up. It runs good in the morning when it is cool outside on my way to work. In the afternoon, however, I get about halfway home and it starts missing and continues to do so until I stop and let it cool off. Any ideas?

Welcome to AF. Low fuel presssure, bad plug or wire , lots of possibilities, there is no quick answer here.

Ok well I guess there is no cheap way to figure it out. Trial and error I guess. I have noticed that when I drive it hard it tends to run rough but if I just cruise with it easy, the car runs perfect. It also runs rough when the fuel in the tank gets under 5 gallons.

I would start by changing spark plugs, plug wires, fuel filter, and air filter.

ya mine does this too just not as bad i put fuel injector cleaner in every other time i fill up too this helps since cadillac fuel injectors get dirty really easy