Hi,

Well I did not see how it started up on the video but you got it running and it hitting on the cylinders! A good thing! It is knocking from a lean mixture and the computer making timing adjustments due to the knock sensor!
The computer is trying is best to get it in tune!
The trick is the engine should fire up straight away without intervention of you using the gas pedal.

The engine in this "present state" is not getting enough air and fuel mixture to get up to the speed of750 rpm to idle properly.
The idle air control valve is not working at all!

The throttle plate is and must be totally shut closed! Since, there is a lack of air, it appears to be like it should be!
The IAC all by itself, should be, adding auxiliary air to bring the idle up, to actually race the engine up and over 1000 RPMS when starting all by itself. Then it should idle back down immediately.
It apparently is not doing anything of that nature and tells me it has a big problem.

This can happen several ways!
The IAC is totally stuck or shot to pieces! IF the IAC has more than 80K or up to 150K be suspicious of a bad IAC.
Check that the IAC is plugged up and all the pins are seated properly.
I have read that on some earlier 80's cars the two cables can get switched because those IAC's have three pins. I have never checked this out because I'm the only one that ever touches any of my cars!
Your 1989 EZK computer IAC only has two pins because it has a spring loaded auto return position, so it only opens up by a signal.

The throttle switch can be bad or not adjusted correctly to the throttle plate and is not telling the computer to make it idle.
Verify that the switch is working by using an ohmmeter for continuity. The reading should show a change of state reading in either direction and upon the wide open throttle setting on two of the three pins.

The IAC can be tested if removed from the car. You can use a nine volt battery to trigger the vane inside to open by applying its current to those two pins.
I use nine volts to simulate the actual system voltage available when the engine is being cranked.
When the engine is cranked the valve is required to fully open up!

There is a diagnostic pin #6 that will test this and other things on the car, but you have to listen very carefully as it goes through a sequence. The IAC is best attended to personally with hands on attention for best results with several touches with battery current to know it works everytime smoothly.

Hope this helps give you a place to dig!

Phil