I have a 2000 i30 base model and i recently had all the belts replaced and water pump. With that said on cold starts at the peak rpm when is initially starts there’s a mechanical squealing/grinding noise that happens for a split second then it goes away and it only occurs when the car has been sitting for a while mainly in the morning or after work the climate right now is highs of 57 lows of 42 also on two days back to back on a cold start the car started but rev very weakly like it went up to 1k rpm and died that happened 3 times on both days then the car roughly started and stayed running and ran fun afterwards. If you guy have any insight it would be greatly appreciated.

The attached video is of the cold start and the noise. I didn’t get video of the low rev and dying.
also i thing its the starter but i wanna know what you guys think thanks again.

 

car start + squeal, in my experience it's bad quality belts, since you mentioned that you recently had them changed... I would go back to the guy that did the job and complain, obviously they are not quality

As for the revs being weird, the ECM is getting some funky data from somewhere, I would start by checking the MAF sensor, the IAC valve and throttle position sensor, all costly parts so best to test them rather then taking out the parts cannon.