This really sounds like a management problem.

The KE-Jetronic always injects extra petrol when the starter motor is turning, warm or cold engine.
Directly after the engine runs, mixture is enriched for a fixed period, warm or cold engine.
Then the system detects the engine temperature en from this fact the mixture is enriched until it is 60 C.

It is unlikely that all of this is broken at the same time in the KE-Jetronic, so a (temporary, just to check) swap of the Bosch computer would maybe solve the problem.

Cheers