Help with 4.0 Ford EFI VS 4.0 SOHC

I have several problems my explorer 2000 began to make noise and accelerate alone and suddenly lost strength and when he turned it out to turn it on, it costs him a lot to start and now he does not start or to put the scanner and ehnotado that apart from turning on the board the Theff the insurance does not lower or go up and the velocity lever is locked when trying and they sell me a 4.0 engine of a 97 Motor because they tell me that they have to be D 3 chains and I do not know how many this EFI engine carries and if the accessories such as distributing oil they are on a different side are affecting to see if I buy it or not