coolant flow to ISC and IAC

[fixkick]

welcome.
those 2 are hosed in series, if one of the 6 ends are clogged, the path blocks the 1998 here, has no top huge main air pipe induction heater, its deleted here in 1998
so only ISC and IAC are in series. and only 2 hoses not 3 hoses. like 97 and older.
back flush all hoses here, and both devices, and water will flow.

is thermostat bleed hole up hill? it must be, so you can fill at RAD neck slowly. and get a full fill cold, run engine with rad cap off
and keep adding is it needs it , at one point the water begins to expand and overflow the rad cap. now kill engine and cap off
then start engine let it get warm idling, let cool and check rad fill at rad cap, and more 50% AF now. (keep side tank 1/2 full at all times or per guide)

the induction hose is missing on 1998 here.
so the ISC hose is sucked at the rear of the pump, that nipple must flow water. there on that funny #5 manifold
the other hidden nipple is below the thermostat goes to IAC, this is hot pressureized water.