Probably fuel starvation

On the way back from the OMC picnic I noticed that on the freeway at 5500 rpm I would lose power...as if i had a rev limiter. The engine runs and idles fine at all other times. Before I left for Los Angeles I put in some carb cleaner and all worked fine....even past 5500 rpm....but now something's changed.

Apparently I'm suffering from fuel starvation but I wanted to be sure of all the things to check....I'll probably start with the filter and then maybe get something that allows me to check fuel pressures. I have heard about that gas tank sock thing too. Plus maybe this is a good time to put in an electric fuel pump.

Any other things that might be causing this? Thanks,
Mike