It would be a very easy test to run it on a separate fuel supply. This is common practice for doing a "Diesel Purge" on the fuel system on Diesel engines (engine is run and car is driven on the fuel system cleaner alone). I use a Gatorade bottle with two holes in the cap (for supply and return line). Run a hose into the bottle from the inlet of the fuel pump (temporarily cap hard line coming from tank), and also a hose from the return fitting of the fuel filter (temporarily cap hose returning to the tank). The supply hose should be near the bottom of the bottle, and the return hose just needs to drain back into the bottle. Secure the bottle somewhere in the engine bay away from the exhaust and any source of ignition (faulty plug wires etc.). If the car runs fine on the test drive, you have a problem with a metal fuel line, or a colgged fuel puck up screen in the tank.