[Jamie '92 968]

My '92 968 (135K miles, original clutch) recently developed an occasional shudder during acceleration.
It usually happens at low RPMs (~2K to 3K) when I give it near full throttle.
The shudder is pretty strong and there is a definite loss of power.

It first happened about a month ago on the way home after spending a small fortune at the dealer for a new lower balance shaft cover seal (I believe this involves removal of the timing belt). Coincidence?? I should have turned around and taken it back, but I down shifted and the problem went away. It was OK for several days before it started to reappear every once in a while.

I'm thinking timing, fuel pump, clutch , differential, ???

I had a local shop (not Porsche specialists) take a look last week, but of course the problem did not show up for them.

Any ideas on the cause, or suggestions for diagnostic steps would be very much appreciated.

THANKS!