Well if you are in 5th in the snow you are probably doing 50+ which might not be the smartest thing in the world. Or you are lugging the motor at too low of a RPM and its just jerking which any motor will do if you lug it too low. Or if you have a 99-up with traction control and it detects what it thinks is wheel slip its going to kill power momentarily which would account for it too. More details.
2000 Mustang GT Steeda build #48. Bolt ons, suspension, Novi 2000.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.