This may be a computer problem
I am writing this e-mail on behalf of my father, Bill O’Marrie who has a 1994 Ford F-150 pickup truck with a 302 cid engine. He bought the truck from a dealer and two weeks later a rod came out of the side of the block. He called the dealer, who said he would pay for an engine to be put into the truck.
The junkyard found a 1990 Lincoln Town Car engine and it was put into the truck but the truck has never run right. It has no power, it misses, floods and then stalls. The only thing it will do is idle. He took it back to the garage and they said that they had trouble with the engine from the start, but there was nothing that they could do. To make matters worse, the dealer he bought the truck from died.
Many people have looked at the truck and no one has been able to tell him what is wrong. The Ford garage told him they put the wrong engine in the truck; that only a 1994 or 1995 engine will work in this vehicle.
It is not accurate to say that “only a 1994 or 1995 engine will work” in your 1994 truck. Either the engine is broken or there are incompatible parts. A basic engine diagnosis should reveal whether there’s a mechanical problem, such as a broken valve, bad compression, large vacuum leak, etc. An electrical evaluation should disclose problems with sensors, wiring harnesses, and so on.
However, it is entirely possible that all systems and components are working correctly by themselves but not working properly with one another. More specifically, the original engine control computer in the truck may not be compatible with the replacement engine. The solution to that would be reprogramming the existing computer or replacing it with a new unit.