I have a 2003 1500 ram. I bought it use, it reads 160k but last owner said he replace motor 80k miles ago, he had no papers to show for so im not sure if true. a mechanic checked it out with me and he said there was a big possibility that something was done to it . little after I bought it it overheated do to the gasket in water pump was bad, I wemt ahead and replace thr whole thing. a week later went to a gas station and went I got back to my truck it wouldn't start, called mechanic and he said to hit the tank a couple of times and crank it and if it starts to get my butt home so i did, I might had a bad fuel pump. I went ahead and replace it with new one and nothing, cleaned out the lines and nothing, changed the sensors next to the throttle body and nothing, cleaned the throttle body and nothing, no codes came back when put a tester to it. I found the truck revving really high and kind of getting stuck and bugging out a little when pressing gas. pressing the gas is the only way to start it also before changing the sensors I couldnt put it into gear because it'll shut off now it doesn't do that but still revving high. PLEASE HELP!!! the guys at the dodge dealership couldn't come up with anything else besides what I've done already

 

If you just put another motor in it, take it back to them.