5.0 missfire..?

[mustang112]

im close to finishing my build...
im having a few issues with my timing right now i think... when i have it running on the stock ignition and i rev up the engine to around 3 grand and let off it tries to go back to idle and dies.. i was thinking it was choking on itself because of to much fuel on the deceleration... so i hooked up a msd 6al and now it doesnt die but it feels like it is missing around 3 grand and i cant rev it past that. at times its also backfireing.. anyone have any sugestions.

right now the timeing is set to 0 degrees... ive looked it up and it says to set it to 10 degrees advanced but when i do that it sounds like it wants to die... but this is also with the 6al and i havent tried to set it at 10 adv with the stock ignition yet.

its bored over .030
has x cam
stock distributer.... which im thinking may be part of the problem because when i hook up the timeing light it fluctuates about 5 degrees or so.
new plugs
new wires

let me know if you need more info, thanks. adam

[zmcnutt]

any vac leaks? those will get you every time

[draggin50]

When you was timing it did you pull out the spout connector?

[draggin50]

Also 10 to 12 degrees without the spout connector in should be good.

[draggin50]

What all is done to the car? What year? Speed Density or Mass Air? Fuel injected or Carb? What firing order are you using?

[mustang112]

thanks guys... got it figured out.... i messed around with the timing a little and took off the msd box and now it runs like a champ.