I just replaced the head of my 1993 honda civic SI Coupe and when i rev it up past vtec at about 6,000 i lose all power and if i do not clutch it and shift right away it gets sketchy. it feels like someone shut the ignition off while you're driving. I am thinking it is valve overlap. Did i time it wrong? is there a vaccum leak? i know there is a vaccum leak somewhere. i hear a high pitched ringing sound but cant tell where its coming from. any advice would help. I am taking it to a foreign car specialist but i wanna keep the bill low so if there is anything i can do to fix this problem please let me know!