D21 Z24i idle screw not changing idle speed

[Dattebayo]

Hey, so it's probably a dumb question, but what can it mean if the idle screw doesn't affect the idle when the engine is very well warmed up?
I will try it again when it's cold in a few hours to see if any difference...

[JB'sTitanXD]

hmmm...not sure i want to say the idle adjustment is frozen up.

[Dattebayo]

Update: Same result when cold.

Anyone know anything about this? It's backfiring under medium and hard acceleration, but it's more like the exhaust side plugs are igniting the fuel rather than a typical backfire...
I hit the pedal and it goes: put, put-put, BOOM, and smell really wet gas, moving either fast or slow. The you see a nice cloud coming out the tailpipe too. No word on whether they see flames, though. That could be cool, actually. :p

I'm starting on the spark plug replacement today, but I need to know what to do about the idle adjustment not working.

[Dattebayo]

Update update:

Replaced plugs and wires, sputtering, popping and backfire-like symptoms gone.
Idle screw still not working. Adjustment to the wax-thing doesn't work either.

Does anyone actually still work on these old Z24 motors around here anymore or am I just jerkin' it?

[JB'sTitanXD]

how old is the carb? have you tried to remove it and clean it well

[Dattebayo]

Well, as per the title description, it's not a carb, first of all...
Second, the TBI is OE as far as I know. I'm probably the 15th owner of this thing.