Hey guys, got a problem with 2002 ranger 4x4 4.0 v6. On start up does just fine, then get up to about 55 mph od light starts flashing and at that point shifts hard from 1st to 2nd. Every thing else is fine. I can shut off for a short time and restart everything fine again until I get back up to speed then od light comes on again with same problem. Any help would be appreciated. Thanks in advance.