Wont run

The car cut off while I was driving it like it ran out of gas, but it did not. We have changed the fuel pump, fuel sending unit, I put a fuel pump relay on it because it was missing, a new cam and crankshaft sensor, a used computer which I reset and used fuel main relay, fuel filter, all spark plugs, and it has a new battery. The timing is not off. The engine fuse blew so I put a new one in it. The car is getting fuel and fire, but two of three coils are not firing. The car turns over and is a little sluggish like the battery is weak but it is a new battery. Also ran another ground from the battery. After turning the car over many times, it will crank but it runs at very low rpm's
and cuts of as soon as I give it a little gas. A guy changed the power transistor unit, but it did not help. The computer wont read so we cannot get codes. The old computer would not read either. Please help.