This sounds like a shortage or an overheating problem.
Have you looked at the printers main board for shortages? (Maybe black/brownish spots)
If that’s okay, try and measure the temperature of different parts of the board while printing.
Check this for parts like steppermotor drivers and headers.
(Be careful while doing this, try to not touch anything on the board if possible because that could lead to a shortage or you could get zapped)