[Mgs] Down on power -- where to look first?

[Simon Matthews]

I took a drive in my daughter's '71 MGB-GT yesterday.

It felt like it did not have power at wide open throttle. It starts
fine, ran fine with small throttle openings, but when I floor it,
nothing happens. Flooring it results in a slight hesitation, then no
more power than light accelerator depression. This isn't a high rev
problem -- it happens at 2000-3000 rpm.

There is no noticeable miss -- nothing that would point to an obvious
ignition issue. The problem is steady-state -- hold down the throttle
for a while and still nothing happens.

So, where do I start looking? I plan to replace the plugs, check the
distributor cap, points, etc.. I did pull the vacuum tube off the
distributor when replacing the valve cover gasket, but I made sure
that the tube is in place a both ends.

Simon