I bought this truck off of someone else
(2006 Dodge Ram 1500 4.7L V8) and I was driving it one day and it just overheated so I checked all the fluids and everything was good but just today I checked the radiator cap and it didn't have anything but the coolant/antifreeze resivor is full where it should be. I can only turn the truck on by jumping it and once it's running I step on the gas pedal and the rpms go up and once I let go the rpms drop too low and the whole truck starts vibrating really bad and I've jumped it a couple of times and it keeps doing the same thing sometimes it doesn't even want to turn on.

 

Is there a check engine light on? Sounds like you have developed a leak in the coolant system. The biggest concern would be that you have a blown head gasket or cracked head.

 

Do a compression check. Sounds like you got ripped off.

 

I hope you got a smoking good deal on the truck! Did the truck come to you with problems or did the problem develop under your ownership? Did you overheat it or was it sold to you with that condition?
- If you are a mechanic, tinkering, type as well as willing .... You know what you have to do. Park it in a good spot, roll up the sleeves, and get to work on it for the next 2 weeks. Compression check, then pulling heads off, machining, rebuild/replace parts as required.
- If you are not of the fixitup type, a) return the truck to the seller if you can, b) cut your losses and resell fast as you can, c) get ready to buck up at least 1500$-2000$ for a shop to diagnose and repair head gasket and minor valve job for you, d) worse case, they'll say you need a whole new engine, 6000$.

a cross reference, similar/same issues: http://www.dakota-durango.com/forum/...d.php?t=453978

 

Sounds like it dropped valve seats from overheating. The overheating was the first problem so replacing the radiator and water pump once you have it running good would be a good idea. Compression test will tell you more then any other test. Replace the timing chains and guides also. Not a fun job