we gather you replaced the 2.8 V6 with Another 2.8V6 ? from what you just "said", the "Starter" still works. the engine is" turning over" (spinning), so your problem has nothing to do with the starter. you should be looking for: Does the distributor send spark to the plugs ? Are the fuel injectors supplying fuel to the cylinders ?
If the tach doesn't move while cranking you're probably not getting spark. If that's the case it's likely a bad connection to the ICM or coil or a bad ICM, pickup coil, or coil. The ICM can be tested for free by O'reilly's, Autozone, or other parts stores. If the parts are good the connections may be loose. Look for brittle, broken insulation on the wires. You can get new pigtails and spice them in using solder and heat shrink. Also check to make sure all your grounds are connected and have good contact to bare metal. When you get the tach moving while cranking you'll probably get some kind of running.