I have been at this for quite some time 83, 280ZX,non turbo. Number 4 is dead, Hers's the things I have tested and or replaced. Starts good, poor Idle, no power,Compression good, Vacuun apprx. 18 at idle 750 RPM, New plugs, wires. cap, rotor, Rebuilt Distributor, Replaced injector and all seals, replaced coil, Cleaned connections, At both the injector and ECU. trust me, I've got GOOD spark, (found it the hard way) I can pull the injector cable from any cylinder and get a rpm change, nothing on 4 runs the same with injector or plug wire pulled. I made a test light and when connected the engine dies. ( test light is a 12V turn signal with 2 probes, will this over load the ECU ) do see some voltage on the #4 injector wire. Any help would be great, I'm thinking the ECU maybe bad. But all other cylinders are working fine. Timing is good. I'm running out of time, this is my daughters car and she will be leaving for college in 1 week, HELP PLEASE.