Dodge ram 2500 runs good when its cold, stalls when its hot????

What is your question?

I have a 2005 Dodge Ram 2500 with the 5.7L Hemi V8, 4WD. This problem started over the spring and summer months. The truck started stalling when it was hot outside, once it is warmed up it dies, sometimes it restarts right away, others it takes up to a half hour to get it to start again, and it seems to be losing power when it is hot outside. Now that it is colder outside the truck runs just fine and has all the power it had before this issue started. We have replaced the coil packs, spark plugs, and air filter, and we did all of this before it started to get cold with no luck on fixing the problem. What could we try to replace next without going overboard and going to the shop? He can work on things if he has an idea of what may be wrong with it.

What makes this problem better or worse?

temperature outside

How long has your 2005 Dodge Ram 2500 had this problem?

since april