OK I have a 2002 X5 with 142,000 miles on it

My symptons are when I first start it up after its in the garage when I put the truck in reverse it acts like it wants to stall and sometimes does.

The idle goes down and it shakes if I put it in neutral its fine


I have replaced the following so far.

DME
Air temp sensor
Oil crankcase
hoses
idle control mod
O2 sensors
Power steering hoses

It runs fine once it warms up and you only see the issue when I put the truck in reverse?

I cannot afford any more guesses at this point please help!!!!!!