Fuel help please!

[Touge86]

I am getting fuel starvation.

Here is my set-up:
Walbro 255 pump
20 valve Blacktop
stock gts fuel lines
stock gts tank

Here is whats happening:

It started that the fuel would cut at high RPM's, or around corners. I tried a fuel system cleaner but it basically shut the system down. I also changed the fuel filter up under the bonnet. Then I bought a new strainer/ filter for the fuel pump. The car ran strong around the block, but then went back to basically less than a limp mode. I was sure it was a combo of a dirty tank, and bad fuel pump. So today I bought the walbro, pressure washed the tank, and put all new gas in. It worked great, for about 5 minutes and back to where we started. The car idols just fine but is just dying under any strain at all.

I guess that since I ran maybe 10 miles since i changed the fuel filter maybe all that bad gas clogged it back up? I suppose the fuel lines maybe are clogged as well?

I am really kinda stumped at this point. Any ideas?