Ok, here we go.... I have a 67 coupe with a 69 302 engine with an offenhouser 4bbl alluminum intake manifold and a holley 4160 600cfm carb. w/vacuum secondaries. The old point's style distributor has been changed to a magnetic pickup assembly w/vacuum advance. The car was running fine if a bit rich untill recently. My problem is, whenever i stomp the gas (in park or drive) my carb. makes a huge sucking sound then POP! right back up through the manifold. This only happens from a dead stop. When i'm already cruising along and I stomp it, no problem. I thought it might be the power valve, so i changed it along with a new accelerator pump diaphram. Still does the same thing. Also, I've noticed a slight miss at idle. Please help me solve this problem. Any comments are welcome..... thanx!