Alan --

If you have fuel pressure, with the K-jet system you must have the right fuel pressure. The flow to the injectors is controlled by the fuel distributor, which uses a complex mechanism for metering the proper flow to injectors based on air flow and also on a control pressure. This control pressure (the control pressure regulator -- cpr) intends to send more fuel with a cold engine. Ironically, a low fuel pressure richens the mixture, and a high fuel pressure leans the mixture.

The control pressure rises with rising engine temperature. Thus, the mixture is leaned as the engine warms.

You need to make the appropriate fuel pressure measurements at the cpr using the proper pressure gauge. This will tell you if the control pressure is wrong or if the system pressure is wrong. The Volvo manual provides a graph of acceptable pressures for different temperatures.

If only the control pressure is incorrect, it means you must replace or disassemble and clean your cpr. But if the system pressure is wrong, it can be a bad fuel pump (low pressure) or a regulator problem (high pressure).

According to the Volvo manual, two things can cause high system pressure -- a blocked return line, and a failed (or plugged) fuel pressure regulator. This regulator (which is NOT the cpr) is screwed into the side of the fuel distributor.

But before you dig into fuel pressures and regulators, confirm that the sensor plate in your distributor is free, clear, clean, centered, and swings up properly.