Hello, i have had this extremely infuriating problem the last 2~ weeks where the idle jumps from about 600 rpm to 1000 rpm at a constant pace, when i press the gas it tries to stabilize a little bit but yet it continues.
(Here's a vid demonstrating it https://imgur.com/n3dr9J2 )

What also is probably a symptom of this is that when i just drive around and press the gas a little bit to accelerate it richens up alot like to about 10.5-11 AFR (it's also really slow to go back to stoich) and when i give it half throttle or so it boosts like 4-7 psi it starts to bog and hesitate a little bit and the AFR's drop to like 9-9.8.
Weird thing is, is that under full acceleration the AFR's are good, at about 11.5-12 it's only under half load it runs like ****e.

This car used to drive like a dream just before those 2 weeks but then it suddenly just started hesitating and suddenly wouldn't start, tho i soon realized it was just me being an idiot because it was just out of gas (my fuel meter doesnt work)
but when i filled it up it started to act like this .

The engine has been modified and rebuilt, the list of mods go like this:
TD04HL-19T turbo with new intercooler and hoses.
Full 3 inch decat exhaust
New Bosch 968 Injectors with resistance grounded.
New 3 inch AMM, new O2 sensor and almost all sensors are replaced.
Walbro 255lph in-tank pump with new filters.
And with supporting chips.
Almost all vaccum lines have been replaced.
All gaskets/seals have been replaced
etc.

 

Sounds to me like maybe an IAC (Idle Air Control) Module. It's located at the bottom of the intake manifold and mine got gummed up. I bet on the turbos though with the blow-by it could also be a throttle body issue, could possibly be gummed up too. Also check your vacuum lines too. I got those repaired as well, not sure if that could be an issue but doesn't hurt to check.

 

I have already cleaned my IAC with carb cleaner and wd40 like 10 times and adjusted TPS to spec.

Tho i noticed the throttle body pulley/wheel had a little bit of play and it could cause my TPS to click so i changed the whole throttle body assembly with another i had laying around, still same issue (i also cleaned it very thoroughly).

Vacuum lines have already been replaced and also the intake manifold gasket.

 

Hi!
Do you have a solution?
I have the exact same config apart from injectors, and I have the same issue as you.
Rich mixture at idle, at half throttle as the boost starts to build up, the engine just completely falls apart. At full throttle it works perfectly.