My 2001 Dodge Ram that I passed down to my son, told
Me he had to turn the key on and wait about 30 seconds and then the truck would start, now it will start but as soon as You take your foot off the accelerator it dies. Any ideas?

 

Moving to the correct section. Check the fuel pressure. Sounds like a fuel pump issue.

 

most likely fuel pump, the truck might be getting enough pressure to start from priming for 30 seconds but not enough once started.

 

Fuel pump only primes for about three seconds... so, leaving the key on for 30, and then having it start..... Certainly check fuel pressure, but, I would also take a stab at cleaning the throttle body/IAC motor.

 

+1 on the IAC, pull that throttle body and carefully clean it all the way around.