Recently, I replaced the original manifold on a 1994 Ford Ranger 4x2 with a 2000 metal intake manifold from a Ford Taurus. Here's what happened:

1. The Change: I first removed the old manifold from the Ford Ranger, then put in the Ford Taurus manifold. It was a tight fit, but I managed to secure it in place.
   
2. The Start-Up: After installation, I had some issues. The truck wouldn't start unless I pressed the gas pedal. Once it started, the check engine light came on if the RPMs got too high.
   
3. The Problem: It seems the new manifold is causing some trouble. The need to press the gas to start and the check engine light at high RPMs suggest something is not quite right.
   

Next step is to figure out why these problems are occurring and how to fix them. This Ranger is a manual, so it's essential to have it running smoothly.

 

Welcome to the forum

Did you use the 1994 fuel injectors?
You need to
If the 2000 injectors are larger then 1994 computer will be calculating the wrong air/fuel mix
Injectors are not the same as carburetor Jets, computers are programmed with injector size so they can calculate correct air/fuel ratio, larger injectors is not more power, its a flooded engine

Also how did you hook up both fuel lines to the 2000 fuel rail?

In a 1994 you can "read the codes" just by counting the CEL(check engine light) flashes

Google: reading ford check engine light (86-94)
Watch the video

3 digit code number list seen here: https://www.therangerstation.com/tec...3-digit-codes/