odd problem

[Nick Craft <ncc@scr.siemens.com>]

Hi list,
I'm having a weird problem with my '88 5KTQ and could really use
some suggestions...

I recently noticed that the "full throttle" switch wasn't working (open
circuit due to corroded contacts). When operating correctly, 
this switch closes when you have "the pedal to the metal",supplying 
this information to the main FI computer (CIS-E-III). 

As soon as I fixed the switch, the car developed a huge
loss of power at high revs only (>5000rpm). It can't even make it to
the red line in 2nd gear, until I lift the gas pedal slightly to open
the switch, then vroom, normal accelaration, until I floor it again.
The problem is accompanied by a surging effect, reminiscent of a misfire.

Disconnecting the switch cures the problem. Also the car needs to warm
up for a few minutes before the problem starts to happen.

I believe the main purpose of the switch is to allow the computer to
enrich the mixture at full throttle. Anyone know why? Car seems to go
fine without it.

I could really use some suggestions of what could be wrong, or things to
test to get more clues. I've ordered Probst's Bosch FI book which may
shed some light.

Thanks,

Nick Craft.