First I will ask is how do you know your running rich other than spitting fuel, if that's the case then your surging because it's running so rich, that will cause the surging. I first would either look into getting a tune for the car from a reputable dyno location or getting a tweecer to tune the car your self. If you don't want to go that route, then I would get an FMU put the stock injectors and MAF back in and go that route. I would look into the tuning aspect as that will be the ultimate better route but it sounds like your right, you are running rich and that is causing the surging idle.
Once you get boost, you need (my opinion) to tune the car for what you have as you have change the dynamics of the engine so much that it's past what the stock tune on the computer can handle and MAF, injectors or FMU can do to use what the stock tune does.
I got the tweecer as I wanted to learn to tune my own car and not be reliant on a person or location for tuning and now it starts just like stock, isn't running rich at idle any more and doesn't have a stutter during cruise anymore due to running lean in the middle of the MAF transfer. It will make your car run like stock only with the power of your s/c.
