Lost of Power

I have a 620i I periodically have a problem with power Engine racing but it does not want to move especially in longer wet grass pasture . Even in 4 wheel and it barly moves in low range It's like something slipping the service light blinks 1 long then 5 short flashes. Is it the CVC clutch and is there a performance clutch replacement I bought it new 2008 has 720 hrs on it Thanks
Frank Valley City, Ohio