The LEDs are No-Name-Brand. Probably Chinese.
They are not 3.2V because they could be 2.8V to 3.6V. The voltage curve in the datasheet is competely different.
If their voltage is actually only 2.8V then the resistor calculation must be changed to prevent the LED from burning out.
The LEDs will over-heat then die if they are not cooled enough. The 4 pins carry away the heat (and one pin is very wide) to a large copper area on a pcb. The large copper area must have cool air-flow.
It is not clear to me you have a current problem. I live in a golf community where the President golf carts use LED tail lights similar to what you have. Out of maybe 10 guys with this cart 3 have had them go bad withing about a year and a half. They are current regulated and have a heatsink. I think there may just be a problem with the white ones.
In any case, lowering the current may help.