I took my 96 Jimmy 108K mi, out rockhunting today. It was running fine, but I had to use 4lo to get thru the mud. After I got on the road, I ran it up to about 35 mph to throw the mud off the tires. ( We're talking thick, adobe mud here.) Ran rough all the way home, and now it really sputters and misses when idling. gets much worse in gear.