1979 VW Rabbit Fuel Pressure
 

I have a 1979 VW Rabbit with a 1.5L FI gas engine, and I think that I might be having an issue with the fuel pressure. More an more frequently, the motor briefly stalls, sputters, and almost sounds like it is missing - especially when under a load and in fourth gear at lower RPM's. I have just recently replaced the distributor, and I know it is timed correctly. It was purring like a kitten a few days back, and then all of a sudden this fuss. It is also hard to start - lots of cranking before it finally fires. And the spark plugs are a little whitish and ashy, as though it is running lean.

I have 160psi compression across all cylinders.

So my two questions are these:
1) What should my fuel pressure be?
2) What is that little deck of cards sized box on the front of the engine block that has two fuel lines running to it and a electrical plug. Is it a fuel pressure regulator, or does it heat the fuel from the residual heat off of the engine? I can unplug it, and everything runs like it should. Perhaps this is gone bad?


Any input would be terrific.

Thanks!

Alan