Steve, if the rpms rise a bit and no gain in speed is often growth. A Go-pro or a mask and a dip will tell you that.
If it is not the growth it could be sticking advance weights in the distributor an easy check just pop the cap and give the rotor a wiggle.
Once the above is confirmed time to look at fuel delivery. Do you have a fuel pressure gage? Do you have filers installed?
Dave Neptune