computer problem 98 intrepid

My problem is that the injectors and the coils will only work randomly sometimes only 2 will work and sometimes just one and it is always the same ones. Sometimes they wont work at all and I have only seen it take a whole cycle very few times. A friend came by and started poking in the fuse holder with a bulb tester i just hope he didnt damage the computer how would i know if he did or didnt. thanks