So this rig has about 240k on it and runs good for the most part until recently. It dies for no reason when accelerating. Like the tach shuts off and there is no power. Used to do it over big bumps on paved roads. Now its bad when I try and pull out onto a main street. It just bucks then finally it runs back to normal. I have taken it to a shop but it never happens when they drive it. I have no idea what it could be. And it is a 5 spd. Anyone know?