Just out of no where driving down the highway my 2004 Chrysler Pacifica sounds like a lawnmower and seems to not want to get up and go. Not leaking any fluids. No check lights came on. Just had an oil change a month ago. 120000 miles. What on earth could this be? When I start it up is sounds like a beast for a few seconds then a lawnmower. Very hard to describe, but lawnmower is the best description!