I bought a 96 dodge

i bought a 96 dodge intrepid 3.5 v6 car that ran great except it was leaking oil from somewhere on the front bottom left hand side of the engine checked everything and put power steering fluid cause it was low i drove it like that for about a month and it drove fine i noticed though that the power steering fluid would constantly be low so i figured that was the oil it was leaking any how one day my boyfriend noticed that there was some little plugs or hoses disconnected so he connected them were he thought they went car ran even better it seemed until the next day i was on the freeway and the car lost power and stalled i believe i ran out of gas cause i was low on it so i had some gas brought to me and put it in the car turned on just fine but started running slow and wanting to stall it started to make a clicking noise and the oil light started to come on and off on the dash so i added some motor oil but that did not take away the noise i made it home like that and i drove it little more that day thinking the noise would go away but it didnt it started to turn off when i came to a stop and it also lost more power and started to make avery loud clicking and knocking noise i mean a very horriffic loud noise so i went through 2 mechanics and the very first thing they said as soon as i turned the car on was oohh thats it the whole engine needs to be replaced but if that were true would the car still turn on and still run? i means it runs poorly and turns off as you come to a stop but it runs while the engine is still cold once its warmed up it will turn off and hesitate to turn back on along with the very loud noise. i dont understand the car was running great how could it hapen from one day to the next?