In January shortly after I replace a failed electronic thermostat we started getting random misfire and misfire with fuel shut off codes. Never the same cylinder.

Some times the car would code after driving 2 miles, other times it would be 80 miles before a misfire. I have to pull over shut the engine off and restart to make it run ok.

I have replace: spark plugs, all coils, air flow sensor(MAF), all CCV valves and hoses, Pre cat O2 sensors, inspected and cleaned and replace O-ring on DISA valve, inspected and cleaned throttle and idle valves, replace intake boot, replace fuel filter, removed cleaned and tested injectors, replaced every vacuum hose I can find, engine oil flush and clean. I also washed and waxed the car.
I even took it into a local european import auto repair shop where the guy charged me a lot of money to tell me he couldn't find anything wrong.

I have done everything I can find to do or someone tells me to do. Also checked the compression which is all good.

This is going on for 9 months, we cant take the car anywhere to far from home or on the freeway due to having to pull over and restart.

I have really like the X5 but this is no longer fun.
Im a 30 year licensed aircraft mechanic with quite a lot of mechanical experience and have up till now been able to fix any issue.

Since all this started shortly after I replaced the thermostat, last week I replaced it again using an BMW brand electronic thermostat. Same problem, no change.

Any last suggestions before i start parting the thing out?
Any one interested in a manual transmission X5 with a lot of new engine parts?