Hello 

1983 vanagon 1.9l waterboxer

I thought it was the rpm limiter kicking in, but it happens on the highway too.  It varies with throttle position and speeds.  It is most noticable on the highway in forth gear around 55-60mph, but is still variable.  It cuts out, but if I apply more or less gas pedal it stops.  

Any testing advice would be appreciated, I am thinking AFM sweepers, but am new to the digijet fuel control system.  

Thanks

Eric 
Memphis, TN area