As the title says I have a 2004 GTI LE RFI (well actually 2 identical ones) and one of them dies everytime i let go of the start stop button. I had them in for yearly maintenance yesterday and the mechanic said the ran great all he did was replace the plugs and drain the old fuel. I can't figure out what the problem could be.

1) At first I thought the key (DESS) was the problem so I cleaned that and still no luck

2) Then I thought it was battery so I swapped it to the other ski and it worked perfectly.

I read on another forum about it possible being a ground wire or TPS.

Any ideas?