1990 tracker isc solenoid test?

[fixkick]

Once I find a new isc I’ll dissect the old 1 and take pics. It clearly a simple valve just not clear what is path of flow - 3 holes in valve and 3 holes in TB. With 1 of those being the polygon shape blocked by gasket.
If I shake the old one it does rattle a bit. But the fact that all 3 holes pass air to one another with no power I’m betting this unit is dead and allowing too much air / lean condition.
We will see - soon

it will not go lean, that valve stuck open is all metered (MAF)  air.  (if that gasket leaked that is unmetered air and yes lean)
it only makes the engine race too fast at idle.

but yes, seems it is struck open or the spring inside rusted to dust.
lots of humid are ran through this for 25 years.
rust happen, there. can be.
good luck with this job, hope you can find parts.easy.
cheers !