Problem with an ATM

Hello everyone in the forum community,
After searching more or less unsuccessfully, I would now like to turn to you for help.
My colleague has a Cordoba manufactured in November 1998 with the engine code AFN. He's been complaining for weeks that it's producing excessive smoke (dark gray to black, looks like it's coming from a poorly adjusted cheap exhaust system, but he doesn't have one) and that it's difficult to start when the engine is warm.
While driving uphill on the way to work (after about 20 km), the car went into emergency mode.
We then first visually inspected the hoses and the intercooler system, and then we took it for a test drive.
After about 1 kilometer, the emergency mode activated again.
Then I proactively replaced the lambda sensor with a diode.
After traveling approximately 50 meters, there was suddenly a loud knocking noise coming from the front, and black smoke appeared at the rear.
"The diode was removed, and it's working normally again, but occasionally it still goes into emergency mode."
Unfortunately, my OBD adapter recently stopped working, otherwise I would have checked the error codes. But could it be due to a misaligned timing belt, or perhaps something related to the ESP system itself?
I know you can't predict the future, but maybe a small hint would be nice.

Happy Sunday!

When it smokes, it usually doesn't get enough air.

Please check all the hoses and pressurize the intercooler system. So, seal it and pump it up.