Mike.

Sorry to hear of your cutout problem.  I also have the exact same trouble.
I have swapped my VW 2.1 ltr. for the Subaru 2.7ltr in my 91 x  5 speed.
Transporter.

My symptoms are.  Van starts up nicely and idles ok.   Start driving until
the van reaches normal operating temp.  Continue driving for another few
minutes then ( usually within the first 30 minutes of driving ) I experience
the cutout.  My experience is like the entire engine shuts down for a
millisecond, regains itself,  then continues on as if nothing had happened.
Drives ok for another 5 minutes or so then the process repeats itself.

Here's what I have done so far on advice from both the Vanagon List,
Subervanagon List and the XT6 Lists, yes a lot of mail.

I figured that the problem was a sensor or fuel delivery problem.  Basically
I started with a check of all the Subaru sensors governing the engine
performance.  All within specs.  Next I cleaned and flushed the petrol tank
and checked the pressure from fuel pump.  Injectors were cleaned and
checked - all ok.  Cleared the codes from the Subaru ECU - still problems.
Checked the wiring harness   - found a short in the wiring for the Coolant
thermosensor ( Temp 1 Sensor) - fixed.  Test drive  - Still bloody there.

Ok where do I go from here.   I am going to inspect every gounding for the
harness.  Seeing that I am using the VW Fuel  Pump I will check to see if
there is a ground on this as well.  - Thats the only thing I havn't checked
so far.  Also I will be looking at the pressure regulator.

The problem is no doubt going to take some cleaver detective work to find
and once found I am sure we will both say " Why didn't I think of that in
the first place."

HANG IN THERE MAN

Ray Hunnam
Penrith Australia
Please no flames about using the 2.7 flat 6 motor.