Six pack power valve....

Wont help the idle, you need to put a vacuum gauge on it with a long hose and tape it to the windshield or have it on the dash where you can see it driving down the road. When you stand on the gas part throttle then full throttle and see how far the vacuum drops. A 6.5 wont open till the vacuum is below 6.5"hg and you will have to drive it to see. A Idle problem is probably a vacuum leak, what do you have at a idle for vacuum.