Sitting for 6 years?
If it had Ethanol gas inside I would drain the tank ASAP.
Change the fuel filter(s) and fingers crossed that rust didn't get to it.
After 6 years the Ethanol breaks down to water and stuff that doesn't want to burn (even with additives).

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."