I'm currently running a 1989 ERST.

I've noticed on tick over if you pump the brake peddle 3 to 4 times the engine just dies and cuts out. I changed the turbo a couple of weeks ago and now when I pump the brake peddle the engine revs up to 1700 - 1800 RPM. What impact would a new turbo have on this? Can sombody explain the basic sience to me.