Anybody have some advice for......

I’ve been recently stacking amc’s on 2.8 drivers just bringing them up to 3.15 amps but been having flickering problems.

I’ve so far done 10 2.8 drivers with only 4 coming out successful. The other 6 have a flickering problem.
More specifically explained is after i stack a chip i test it out for about 5 minutes. For the first 5 minutes all modes work fine with no flickering.
After that time they start to flicker and only get worse.
I have tested them installed in a p60 pill and just on their own with a little wiring set up i use to test.
Anybody have some advice on what problems i should be looking for because i can’t find any bad grounds.