E46 Heater Blower Issue

[RLK500]

All, anyone have any wisdom to shed on the following issue. E46 W Plate, the blower motor seems to have a mind of it's own. Cuts out of it's own free will, normally when you require it the most.....generally also seems to be lacking the real oomph it had when I first owned the car. The final stage resisitor has been repalced with no noticeable difference.