I bought a 03 rio 1.6 DOHC that had bent valves / timing belt break but the pistons and bottom half was undamaged. So i went to a Salvage Yard and found a head, but it was a 1.5 DOHC head off an 01 rio. I was told it would not interchange, but i had no choice being that it was the only one I found WITHOUT BENT VALVES within a 100 mile radius, and out of 8 Salvage Yards, so I went for broke and did it. I had to change a few things but I got it to fit. It runs and idles just fine, but the problem is when you put it into drive, it has no power. You can literally stomp on the gas and the car will barely move. And no check engine lights come on. Then i thought it was the cam timing, do to the difference in the size of the head. So i retarded the cam timing, it has a little more power but still no take off.. I also called the part store to check the computers, they do have the same part number, But is it possible that the 1.5 computer is slightly tuned differently than the 1.6? I NEED HELP, any ideas or suggestions would be greatly appreciated.