In the past few weeks, our Dodge 600 has challenged us significantly. We could drive it for a short distance and it would start again fine one day then the next time it would not. It would start fine in the morning and my wife could drive it to work (about 20 miles). So long as it sat for at least 4 hours, she could start it and drive it home. A couple times she could make a stop at the store and it would start again so she could make it home. Another time it would not and I'd have to go get her. If we gave it a few hours, it would start again and we could drive it home. More and more though, it has to sit overnight and will only start early in the morning. It seems to be related to the heat of the engine and/or heat of the day. The fuel pump (in tank) & fuel filter were replaced about 1 year ago. Attempting to determine what to try next. The one Dodge dealer only wanted to provide assistance if we brought it in for a diagnostic test ($92). Another one suggested fuel pump relay - did not provide info on where it was located and would not be able to check out car for another week. So we muddle along.