Michael,
You installed 8.5 power valves?
With a 252* cam you will only pull 8 or 9 inches of vacuum.
That isn't the correct power valves to use. They should be 3 points below your vacuum reading at idle. Try using 5.5 power valves. The # is when the power valve opens and dumps gobbs of fuel into your engine so if they open too soon you'll foul plugs and run like crap and won't be able to set jet sizes or air mixture unless you get them right first.
Good Luck,
Perry.
