I must correct myself; the 190/2.3 did use KE-Jetronic from '84 on.

It contains a feature that the OP may not have encountered in his Volvo experience; the electrohydraulic actuator (EHA). The EHA is a mixture controller in the fuel distributor (FD) that responds to feedback from the O2 sensor. In addition to responding to exhaust oxygen, it also delivers an enriched mixture during start and warmup. Along with the possibility of a leaking accumulator, a defective EHA, or the lack of a signal to the EHA, can also cause difficult starting. If the accumulator is just starting to leak, the exercise of "whirring" the fuel pump 4 or 5 times to build fuel pressure before cranking the engine, will often identify the accumulator as the culprit.

The EHA is located on the side of the FD, and has an electrical plug attached. Unplugging the EHA connector MAY give some indication of the source of the problem. MAY, because the lack of a signal and an unplugged connector will have the same effect. With the engine warmed to normal operating temperature, unplugging the EHA while running should produce a change in idle if the EHA and the signal are good.