Maybe, the TT auto box in it has done about 75K km so I would have thought its still good.
But I'm now pretty sure having done the full conversion, including the TT auto box, it's more likely to be the lack of T.C.. I will also have the wiring around the fuse box in the engine bay double checked just in case. But thinking about it, it really is only happening on WOT which I think does indicate the lack of T.C.
If that is the case I will get a stock T.C. unit and have it switched off.
I'm just after getting this little issue out of the way. I dont imagine harm has been done to the engine or the box as I've not done many miles with it really like this. But obviously I need it sorting before something does get damaged.