Fuel pump, SSV, or bad gass?

Ok here's the thing it's not bad compression not hot start problem at all. As the title states my thinking is one of the three. Here's the problem got my new header gasket on (car sat for two weeks on 1/4 tank) started her up she started right away no trouble there let her idle for a bit because she sat there for so long. Took her out for a spin all was good through all RPM ranges. Went got fuel and noticed a hesitation or kick down in power at about 4500 RPM she's pretty limp till she hits about 7k then bam a blast of power she comes to life and goes. Now my thinking is bad gas because it happened right after fill up or condensation built up in the tank cause she sat so long with only 1/4 tank days have been hot and night cool. I also think perhaps fuel pump going bad but why would it spring back to life at 7k RPM. Or SSV seeing if I'm not miss taken is suppose to open at around 4500 and this is where you can feel a drop in power but again why the spring back to life at 7k. BHR coils plugs wires all done at the start of the year. No CAT. And one other thing makes me think fuel pump is if you let her climb slowly no drop in power it only dose this if you push the pedal and maker her go. Pumps never been replaced as far as I know and it never showed up on any service records so it has 140k miles on it. SSV has more than likely never been cleaned ether. Any thought on what I could be would be grate.