computer question

i shut my car off and it wouldent start it just turned over i replaced my coil pack and module and crank senser and no lusk so i replaced my computer in my 90 supreme international i bought one from the junk yard and 4 days latter it went out wase it just a junkyard bad computer mind you it took houres to make it run off of it and the car never ran right off of it coulde it be killing the computers or wase it bad when i put it in

Did you take the chip (I think it's called PROM or something else...) out of your original computer and transfer it to the one from the junkyard?
Might be they gave you a computer from a different size engine?