Vintage Cars: 1969 Triumph TR6 - Keep Engine on, 3000rpm, fuel delivery

Question
I just bought a 1969 TR6 Racing Edition. It has to be attempts many times to start the engine but with full pressed gas pedal. I have to press down the pedal around 3000rpm to keep the engine on. The engine would die off when the gas pedal is without any pressure even after enough warm up (5 minutes of engine on at 3000 rpm). The past owner told me that he found the fuel filter dirty and had to clean due to rust inside the fuel tank. He suggested to have the fuel tank vacuum, cleaned up. One technician guessed that it could be due to vacuum diaphragm inside the carburetor ?

I just want to have the car starts easily and stay on just like my other cars. What is the appropriate fix with minimum costs.

Thank you.

Answer
an engine needs three things to run, spark , fuel and air.
sound like she is either starved for air or fuel.  are you getting fuel delivery to the carb? What are your fuel pressures.  Is the carb adjusted correctly, is the choke stuck open or closed?  Can you smell gas?  Is your fuel pump working, filters cleaned.

Sorry hard to help without more specifics.
My guess would be carb choke stuck closed or fuel pump and fuel delivery