I have a 74 450 SL with sudden onset of erratic power. The engine will stop running on 4 of its cylinders (numbers 1, 4, 5, 6).
I've pulled the spark plugs, they are good and are getting a spark. I pulled the electrical connectors to the fuel injectors and found that there is no power going to the four dead cylinders when it acts up. During the times it fixes itself, there is electrical current flowing. The Haynes manual says the ECU is near the battery but it isn't. Another source says it is on the firewall beneath or by the passenger floor mat but a cursory look couldn't find it. Is it there? Could this be where the problem is or should I look elsewhere? I don't see a common thread between these four cylinders in the electrical schematics.
Thanks for any input.