dude MSD will cause some freaky ass issues if not maintaned, mine is kept INSIDE the cab to keep crap like this form happening, have you ever noticed the tach jump or die at all?

i would swap out dizzys, check out distributor king, or www.streetimports.com they have dizzy for all OBDs at a good price, if you had a wideband we could have found out if it was fuel related