My idle goes down to about 500-600rpm at idle, I need it to stay at 600, but there is no idle adjustment on it, it is an internal distributor system, how can I adjust this?
You don't. You test your throttle position sensor and adjust/replace it.
Edit: If a bad tps is the problem, no tuner is going to fix it. If it doesn't work now, tuning it isn't going to change anything; it'll still fluctuate.
