I'll try to make this as short as possible. So many things have
happened and many parts have been replaced, I need to tell the whole
story...sorry :(

Six months ago my VS ute(AUTO) wasn't starting properly and was
stalling while idling along at 40-60km/h. I took it to the dealer for
diagnostics and front brake pad replacement. They couldn't find
anything, so they did a throttle body clean and set the idle a little
higher. While driving home my brakes weren't working properly(this
wasn't an issue when I took it there) and it stalled on me aswell. I
called the dealer about the brakes and they adv me to bring the car
back and they'd give me a quote, I told them not so nicely where to go.

At this stage I didn't care about the brakes, I wanted the starting and
stalling issue fixed, so I replaced the battery, didn't help. Auto elec
was the next thing, the starting issue was caused by a loose wire from
the battery to the starter motor(still can't believe the dealer didn't
find this). He got the car to fail, but it wasn't registering any fault
codes, he replaced the idle motor, but it didn't make a difference. He
tested all my sensors, nothing.

Off to the brake specialist. My brake booster had an HUGE crack in it.
He replaced this and things went OK for a while, the idle was still not
quite right, but the only time it tried to stall was when putting the
car in reverse.

It started stalling again, so I took it to a mechanic for a service, a
tune and some diagnostics, they couldn't get the car to fail, but they
found out my TPS was stuffed, so it was replaced. Things have been OK
since then.

My problem now is working out what is causing my car to near stall when
being put in to reverse. The trans #*$& itself and was replaced with a
reco at 109,000km, it's now done 175,000km and I've had it serviced
three times in the last three years(last service was 3 months ago) and
I haven't had any problems with it. When the car is warm and I put it
in reverse, the idle drops REALLY low(about 200rpm), and then shoots up
to anything between 600-1500rpm!! But most of the time it doesn't pick
up and the car stalls.
Please help me, I'm going out of my mind.