[coconut 321]

Pete; I have the same system, L-Jetronic, on my '74. Your problem looks to me to be electrical, which means that you should check all terminals on the wiring harness for continuity, especially the grounds. Also check the wiring for continuity especially the Cylinder Head Temperature sensor located at cylinder #3. It determines the richness of the fuel mixture by resistance. At 68 degrees the resistance should be 2000 to 3000 ohms, at 122 deg. it should be 700 to 1000 ohms. Good hunting.