Hi Tim,

Tim, it may just be that the idle valve cannot  compensate for the
current adjustment of the Fuel injection system. or you have an ECU issue.

So if you don't get a better decisive offer I'd suggest  swapping ECUs.
Then if the issue persists, then I'd reset the Fuel injection
adjusments. Spring Tension, then idle, then CO, all of which the idle
valve depends on to to a degree.

Mark Keller
91 Carat