Need help from some pros

[Adger Smith]

As Rob said, more might need to be checked if it isn't DA causing your lost ET & MPH.
SO: after re reading your posts....
Get rid of the Vac advance. Race cars don't need it. Vac advance is only on cars for gas mileage at cruise speed. I've never seen a race car that cruises or needs part throttle gas mileage. :~) Check the mech. advance & make sure it is only going to a total of 36-38 to start with or use your old tune up setting. Then check the valve setting. Then check the spring pressure. Run a compression test on all cylinders after the valve setting or run a leak down instead of compression test... Leak down test is best. If it stalls less you are down on power. Carb linkage slip is a good thought too....Hope this helps you find the lost power.