The correct (official) speed is 850 RPM.

Don't know why everyone seems to have missed this but 500 RPM is no good what so ever and will cause the stalling you are having, it can also cause a bad idle as the ECU senses it's to low and will compensate via the ISCV.

No problems starting here what so ever, bearing in mind mine is rarely ever used, it always starts first time, again your idle isn't going to help this!

Setup the base idle properly, you should find this will sort most if not all of your issues!

Martin