Shimano XT hub. Two years ago the freehub would occasionally stick when coasting. It would released instantly with a "click" sound. I could never duplicated this on the work stand.
I removed the cassette, cleaned the exterior of the freehub and squirted WD-40 into the freehub as much as possible. The problem continued. Then I replaced the whole hub with a new one since the price of the
a new freehub was almost as much as the new hub. This was 3 years ago. With the new hub I never had any sticking until yesterday. It stuck and released 3 times.
The bike is protected, exposed rarely to rain, and has the least klm compared to my other bikes. I use it to commute to town, and occasionally on long rides (80 to 100 k) that involve 5-10% dirt where I cannot use my road bike.
I have never had a sticking freehub on any of my other bikes
Any suggestions are welcomed.

In no world could the cost of replacing a hub come anywhere near the cost of replacing a freehub. In order to replace a hub, the whole rear wheel has to be disassembled and rebuilt. This takes more time than building up a brand new wheel and would require about 2 hours of time to accomplish. If it was only your freehub that was the problem, changing the whole hub was not going to make the freehub last any longer than if you had only changed that part instead of the whole hub. However, your attempt to fix the problem begs a certain question. The interface between the cassette is static, it cannot contribute to the sticking freehub. Shooting WD40 into the end of the axle once you have removed the cassette is going to wash grease out of the axle bearings, almost nothing will get into the freehub. Did you change the hub yourself?

Yes, I replaced the hub, laced the wheel and trued it. I work on all my wheels. Since the sticking occurred when the wheel was relatively new I decided to replaced the hub. Since I was doing all the work myself the cost difference was minimal.