94 ranger 4.0, When i bought the truck someone converted it to a 3.0,i wanted more power so i have switched it back. i have sucessfully aquired the origional harness and computer but when the job was done the truck idles and revs fine. When i try to drive it and go over about 2500 rpm it falls on its face. The new engine is from a 92 and does not have a cam position sensor, my harness has a plug for one. do i need this?, or can i get the computer for a 92? HELP!!!!