Glad I found this thread! Been having a very similar issue with 987.2 2010 Boxster Base 2.9L this morning.
My PDK has always been a bit lurchy at low speed (bumper-to-bumper traffic)...but never had issues at high speeds or once out of 1st.
Well I just upgraded to a plenum air intake and bigger throttle body ... now the problems are much more pronounced and the dreaded "Emergency Transmission Run" message has appeared almost every day for the last 2 weeks. But nothing was ever very obvious, it kept shifting very normally.
This morning driving to work in the middle of the hi