VW Crafter 2.5 TDI / Power loss when incandescent turntable flashes

Hello, I have a serious problem with my 2006 crafter installed is a BJJ engine 2.5 TDI with 65kw/88PS KM standknapp 190 tKm. the following problem: Sporadic error: Incandescent light flashes (only on the highway) from 2500 rpm approx. 110 to 120 km/h. If you flash I have only about 50% of the power usually flashes then also the engine control light which then usually also stays on. Well a restart of the engine goes again, sometimes you can also drive 200 km without what is, some things go ke ine 10km… After several visits at Boschdienst with error search and memory erasure we changed following parts: charging pressure control valve, all glow plugs, lambda probe, pressure valve from the comonrail, air quantity meter… When reading the error the lambda probe was displayed = changed, then displayed charging pressure error = charge pressure control valve was exchanged, then one of the problems at the touran told me, glow plugs and air quantity meter = changed…. slowly I dedate d I put hundreds of Euros in it and the error is still there !!! I really don’t know what to do anymore! I hope very much here one can help me who has correctly guessed about it. Currently the error 339 ( Lambda probe resistance too high bank 1 ) cannot be deleted. Unfortunately, the Bosch service has no access to the manufacturer-specific errors in the memory…