About 4 months ago I bought a '90 Vanagon Carat and have recently
experienced problems which the previous owners had experienced in '96.
When going up a long hill after about 1/2 hour of driving the van
suddenly loses power (ie. the gas is floored and I can't go above
40mph).  I have taken a couple of day trips and one 3 day trip from San
Francisco to Cambria down the coast and back up.  I experienced no
problems on this trip however is was raining and quite cold the whole
time we were driving.  The problem first occured three weeks ago taking
a trip into the valley where the temperatures were warmer than the usual
SF cool.  While going up a hill there was a sound like a cork popping
and then a great decrease in power as well as the engine sound dropping
from its normal hum to a very low hum.  Shortly after this, black smoke
began to come out of the tailpipe.  It was a very long 2 hour drive back
home with the black smoke and the car topping out at about 45-50.  We
then stopped for about 20 minutes after which the car was fine.  My
mechanic looked at it and said he didn't know what it was.  Today I went
out again to a warmer area with a spare computer, and of course this
happened again, and swapping the computers didn't help.  Does anyone
know what this problem could be or does anyone know of any materials
other than the Bentley book that I could get on Digifant systems.
Any suggestions or info would be greatly appreciated
Amy S.