i have a 4x4 automatic and it shifts hard from 1st to 2nd just about all the time and 2nd to 3rd sometimes i changed the filter and fluid and there were metal shavings in the fluid pan. It started when i hit a BIG SNOW DRIFT and got stuck that's when the problem started. i heard that a vacuum line might be the problem but don't know how to track them and what goes were.what could be wrong and what should i do