Hello everyone,
Sorry to bother you all with this, but I've searched the archives and tried quite a few things and still have the same problem with my 91 240;

Error codes for 1) rich/lean at cruise 2) rich/lean at idle 3) fault at injectors 4) fault in CTS signal

The vehicle is showing all the signs of running rich - rich smell, terrible gas mileage (~15mpg), poor idling etc. Yesterday I pulled the intake manifold and the CTS, tested the CTS cold and hot (100C) and the resistance was in the correct range. I double checked the connections, ensured the cold start injector was working properly (opens with voltage), cleaned the 2 grounds on the intake manifold and fixed up the ground from the head to the firewall. I checked the fuel pressure regulator as suggested in the FAQ (disconnected the fuel return line and there is a lot of gas returning to the tank). There is no fuel coming out of the vacuum side of the pressure regulator. I also checked the voltage between pins 13 and 5 on the ECU, it's in the correct range, as is the resistance when the ignition is on. I'll check the O2 sensor tonight, but this doesn't explain the CTS problem. Not sure what to do. Is there something I'm missing? Should I go to a shop and have the fuel pressure checked? Other ground connections I've missed?

Any help would be appreciated. Thanks in advance.
Matt