well 3 days after getting this car, it decides to start acting up on me...

whenever i go to start the car, after it cranks over i have to keep the key in the "start" position for like 5 seconds otherwise the engine just dies. it cranks over immediately after i turn the key, but if i don't hold it there for a hot second, it dies. i'm baffled as to what could be causing this...

oh and there's this weird whirring noise from 2000-2800 rpm coming from the engine bay, never heard anything quite like it, if there's anyone in orlando who wants to come by and help me diagnose this shit, i'll buy lunch... and beer if it gets fixed

EDIT: it's a b18b block, b16 head, and other goodies with about 6000 miles since the build up