Kipling wrote:
I am suffering from a very erratic idle on a 2.5ltr sve lpg
converted car, currently 58,000 miles. The car is an automatic,
and seems to function fine in all other manners, but, when put
into neutral the revs jump up and down from 1500 to 2200rpm making
the kind of noise you would get from deliberately revving the
engine. The car functions in all other ways ok, when in drive,
with the brake on, there is no rev problem, but then the engine is
engaged... There is a consequence of this, at speeds of low revs,
the car gets a slight jerk forward as it pushes up from the 1500
to 2200. This happens whether or not the car is running on lpg or
petrol,
but doesnt happen when the car is first started up, ie it runs for
a short while before the problem happens.

A general mechanic who has done work for me in the past, said his
fault finding equipment couldnt pick anything up and suggests i go
to dealer and see if their system can locate the fault.

I dont know much when it comes to cars, but have read about lpg
messing up some valves, and i do know that it has some 'valve
saver' fluid bottle fitted.

I run an LPG van, and the general rule of thumb is if it does it in
petrol mode it is unlikely to be LPG related.

Bit of an unlikely one but a problem i had recently the floor mats
are not interfeering with the throttle pedal are they?

nah, thanks for the suggestion though.. i have it booked with the dealer in
the morn