Hello everybody and thank you for your time.

My current issue at hand is (while cold) engine will idle normally, but requires me to blip the throttle a few times just to get it started. But once it warms up for a few minutes the idle rpm will fluctuate from about 1.2k down to maybe 200 rpm back and forth. Also once the car starts and I drive the car while cold, it will drive like normal, rpms climb normally but once the Throttle is let off the rpm will decline rather fast and occasionally drop to 0 and require me to start the engine again.

Now my second issue at hand is there is a knock coming from the engine bay. It seems to be coming from down on the bottom end of the motor. I have driven it today to see if maybe the knocking was the Axles or maybe a motor mount but I confirmed the knocking isn't the Axles or the mounts.

I have been doing tons of reasearch on the idling problem and am pretty sure that i dont have an external vaccum leak (scroll to bottom to see different diagnosis that I have tried)
So my main question here, is there a chance that maybe I have broken something internally creating the knock, that is creating a vaccum leak?
(please keep in mind this is personally my first designated project car so if anything I say sounds dumb, please correct it because I know no better than what the internet has taught me.)
-DIAGNOSIS METHODS I HAVE TRIED-
●Covering hole inside of the TB to the iac
-(result) Engine died out instantly
●Spraying carb cleaner near vaccume lines to check for leaks.
-(result) No change. Idle rpm never spiked signifying any leaks.
●Unpluging iac
-When idle is surging, idle will correct to normal rpm when unpluging iac. Once car is driven, idle will surge again.
-VEHICLE MODIFICATIONS-
●B18B1 swap
●Manual transmission swap(LS)
●Chipped p28 ecu
●4-1 exhaust manifold + cat back
●Cold Air intake