base timing on 1999 8.2

[heavyhammer]

Trying to put our boat back together. Stock cam, new lifters, new rockers, new springs, ecm reprogrammed. We are having a heck of a time getting the timing right, wondering if there is something else wrong. Gone through base timing procedure, can't even get engine to idle unless its advanced to 12*. We are able to get it to idle in normal mode and it run out, but if accelerate to quick it will backfire thru the intake. Just looking for some ideas. Have checked about everything I can think of.