Rrrrgggg. This thing is making me mad!!Help please.

I know this isnt a ford but this thing has been driving me nuts for awhile now. Its my g/f's dad truck. Its a 1993 Dodge Dakota 4x2 with a 5.2 V8. If you start the truck and let it warm up for 1-2 minutes then rev it up (around 1500-2000) the motor starts to stumble and missfire really bad. I hooked up an inline spark checker and you can see it miss on all 8 cylinders. Its got a new coil, spark plugs, cap, rotor, plug wires, 2 ECU's , and a new cat. All of this stuff wasa needed except for the 2 ECU's. He took the truck to a couple of shops and they couldnt figure it out. I ran a snap on scanner and it said that the ecu was bad. I checked the wiring to everthing and its not grounding out, the TPS sensor, both O2 sensors, the MAP sensor, ohmed all of the fuel injectors, and crank sensor. You guys got any ideas? Also if you dissconnect any of the fuel injectors you cant tell any difference in the idle.

I checked the fuel pressure and it sits at the bare minimum of the tolerance but why would that make a missfire. And the spark checker Im talking about is those things you plug into the spark plug then the plug wire on the other side. The light inside flashes red at idle and stay steady during upper rpm's. Well with this truck it flashes steadily untill 1500-2000 rpm's the it flashes sparatically. The engine back fires every now and then while this is happening. It does the same thing when your driving.