Diesel Bombers - Im out of ideas please help

Alright, so here is the deal I just picked up my second 6.5 diesel a while back from my uncle. It used to be my dads truck as well so its always been in the family. Sadly, I have an issue and here it is

Issue :

Starts up just fine runs for roughly 15-30 minutes starts missing and eventually dies until you let it sit for 15-30 min. Just wait though it may not be what you think

What has been replaced :

Fuel pump (3 times)
All Injectors
PMD (Twice)
Injection Pump
Even the Throttle Position Sensor

Everything else that I've done :

Hard wired fuel pump to a switch (Yes it works just fine if I were you I'd doubt my ability aswell)
Tuning Chip by Heath Diesel (Even though it only effects the transmission I wish I had EFI sometimes)(Also have the same chip on my other 6.5)
Wastegate Spring by Heath Diesel (I don't know how you can mess up installing this to the level of engine failure, but some people including myself have amazed me)
New thermostat (Just had a small leak on it I replaced this during the injection pump replacement)
All sorts of new gaskets and all that nonsense I've been working on this all day and can barely think

Final Message
I have done a lot to get this truck running but it really has just slapped me in the face and just said "Nahhhh not today, maybe later tho.' I even tried later and never changed. Ok ok in all seriousness this truck has been in my family forever one day just started having issues, so I decided to take over and try to fix it. It only has like 164,xxx miles on it, fairly clean, just wont run. If you have any ideas or questions please help.