I have a 2012 Titan SL with approx 98K mi. From time to time, generally when its wet and cold out, I will be driving along at highway speed and all of a sudden the truck either hard shifts or hesitates with a dull clunk. No codes, no RPM rev changes, no service lights. Checked transmission fluid, perfect. Changed rear diff fluid, perfect. mechanic cannot get it to do it when he drives it (go figure). Ordered and am going to change the IPDM ECM relay cause I found a similar issue on an Armada site that helped. Any ideas would be helpful. I am not a mechanic so lamens terms would help as well. Thanks.