I have an 83 mustang that was bored 60 over with a voodoo lunati cam max lift is .483 exh. .466 intake and has tons of vacuum under the curb. Full MSD pro billet distributor rtr ignition, edelbrock carb 650 thunder series and bbk full lengths. carb has been cleaned after winter, distributor freshened up cap and rotor, advance auto canister is one year old. car runs fine around town. if i accelerate and hold it withing 2000 to close to 3000 and you can feel missing a bit cruising and I punch it and she rips once the secondaries and advance picks up. seems like i have more issues from 1500 to 3000 putting around town holding low rpms. Carb idles awsome and i adjusted it via edelbrock videos. I have all brand new vacuum lines. added and extra ground from batt post to frame 0/2 wire. New neg wire to block and re furbished the ground strap at rear intake to firewall. I have different springs and stop bushings for the distributor. has the heaviest springs installed now. i have 21 degrees stop bushing. (MSD stock setting out of box). Car used to have a professional tune from competition mustang in spring lake NC. but i have since put gt 40 3 bar heads on it, went from 570 holly street avenger to edelbrock thunder series 650 and an 6AL msd box on it. and a Detroit locker with five lugs, tremec HD t-5. since its old tune back in 2007. they maked the balancer so ive always just gone off their timing marks. how many degrees of timing sweep should i use. is 21 enough or should i put lighter springs in it to try and get more advance that way. i know my Vacuum advance pulls ten degrees when engaged. Im dieing to get it down to Lebanon vally NY drag strip. old set up was a solid 12.0s at 1/4. Any help is greatly appreciated. distributor is pn 8352 pro builet msd rtr. Thanks again.