My car has a b303 cam in it and it isn't idling properly. now before this guy turned my throttle position screw which i found out was not suppose to be messed with. my timing was retarted so i got it but back at stock 10 degrees. when i did that it idled at 1000. now im stuck trying to figure out how to get the idle back down because when i drive it when it starts to slow down it shakes and it also shakes when the car is in park. the car is now running at about 12,13 degrees timing and the problem is better but not perfect it still shakes alittle. this guy said because im running a b303 cam that i might have to retard the timing to about 8 degrees... what should i do.?