I have a 1989 ford F 150 that started pulsing up and down in rpms. I replaced the idel control sensor and the started having a firring problum. I replaced the cap,rotor and ignition module. I have fire and I have fuel at the rail but the engine still will not start. We tryed to code it to day and the computer said to refere to the ford manuale appendige B. We are thinking the computer has gone bad,can anyone help and were can I locate the computer on the truck.