Hi Ken. We have done quite a few poor Hot starting VW's and most of them have been caused by starter problems, In fact one of the first ones that we did was for our Local Main VW dealer who rang us to see if we thought that a slightly lazy starter would cause those symptoms, I said yes, So the sent the starter motor in and we stripped it, Cleaned it out and basically just lubricated the bearings etc ( may have even changed the bearings ) They refitted the starter motor and the fault was cured. That car had already been to another VW dealer and had already had almost every part replaced that they could think of without success.
Good Spec battery and starter motor overhaul would be a good place to start. P,S Don't send me the bill if it doesn't cure it.