Hi all
I have a strange running problem with my 1981 aircooled westy.  The vehicle starts and runs fine, with correct idle.  However, when blipping the throttle when parked, the engine hesitates as if mis-firing until the RPM gets high enough and then it revs okay (maybe 3 seconds).  When driving, this is shown as 'hopping'/bucking when accelerating at partial throttle, or when decelerating at partial throttle.  If the throttle is opened wide, the bucking stops after 2-5 seconds and the engine runs normally on the highway.
 
In addition, power is down on hill climbs and the fuel milage is a low 14 MPG on a highway run at 70 MPH.  All 4 spark plugs have black sooty coating suggesting rich running, and when the throttle is blipped after idling for 10 seconds black smoke comes from both exhausts (EMPI).
 
The problem is I have checked/tried virtually EVERYTHING using the ProTraining Manual and Bentley.  The entire ignition system, including distributor is brand new and timing has just been set.  I have checked everywhere for leaks in the injection system and can find none.  I have done all electricall checks on the AFM and it checks out fine within spec (I even pulled the cover and everything looks well inside).  I have checked the cold start valve, the fuel pressure (only 1psi above the high end of the acceptable range), injectors and resistor impedence (9.2 ohms compared to approx. 7 in Bentley), the head temp sensor is new and I have checked it electrically as well.
 
I have not checked the injectors for leaks as all 4 plugs are sooty and I would be suprised if all the injectors went at once.  All I can think of is the computer, although my understanding is that they are incredibly reliable and don't go wrong ofter.
 
HELP PLEASE - I can't think of anything else to check, and I don't have a spare computer.....
TIA
Michael