Zafira: Engine cut outs?

Hi,

a Holden Zafira has a strange problem that my garage has not yet been
able to fix:

When there is less than 1/4 of petrol in the tank and the car drives
uphill, the engine suddenly "cuts out". I.e., the rpms go down to
about 700-1000 rpms and there is no power anymore to accelerate (the
car becomes slower and slower, but there is no stuttering). The only
thing that works in this situation is to fully release the accelerator
pedal (take the foot off the pedal) and then hit it hard. At this
point, the engine comes back and the car accelerates again.

The car is serviced at Suttons City Rosebery and they have done all
sorts of cleaning in the engine and the petrol transmission, but the
problem is still there. Now they propose to take out the whole fuel
tank and look in there (which will be expensive), but I'm not
convinced that this is the problem. I'm not a car expert, but it
sounds more like a problem with the electronics to me (and another
garage suggested that).

Is that problem a known problem? Does anyone know how to fix it? What
are the experiences with Suttens City Rosebery? I get the feeling that
they just try to make more money instead of fixing the problem...

- Felix

-- 
	       Felix Rauch, http://www.nice.ch/~felix/
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