1994 g20

[factory17]

So got 1994 g20, and took into the shop for a hesitation and rough high idle and p0400 code, I had also fixed 1 cracked vacume line before taking in. Shop couldnt get there 3 diffrent diagnostics machines to comunicate with the ECU.

Rplaced the ECU runs the same, and not throwing any more codes. Checked the TPS readings are correct, new cap rotor plugs, cleaned MAF, and airbox sensor. When adjusting the idle on the IACV doesnt seem to make much of a diffrence when moving in or out, not sure if when adjusting it would normaly go way up or way down for idle.

Basically if you ease the throttle without stomping it it goes down the road, but any quick movement it doesnt like it. So when its at idle if you press the accelerator quick it goes ba ba ba vrooommm?

Any ideas on what to check next for resistance or volts??
All vacume lines seem to be hooked up and not cracked or damaged also.

Thanks for any help in advance

[SoundEfx]

By any chance would you know your afr's?
To me it sounds as if the car is running rich, hence the hesitation and I say this because mine did the same thing.

Check your coolant and your air temp sensors. When I changed mine, it helped tremendously.