First off,the two msprings on the Holley is a bit overkill,as I've learned from experience.One of the return springs should work just fine.Now,to address the throttle stick problem:When you installed the Edelbrock,did you check for proper clearance on everything involved with the throttle arm?Here's what you do,pop your hood,and with the air cleaner on,move your throttle and see if anything is catching externally,if so,adjust accordingly.Also,some times you need an air filter housing spacer so that the arm can clear that.Take a pic of your carb for us and it might be easier for us to figure out what's wrong.