CRATE ENGINE HELP

I just installed a indy crate engine 500 wedge for a friend of mine at low rpms it run rough and will not idle.When i rev the engine it slow about returning to lower rpms. It revs quick i don't think it is fuel problem i have changed the carb and it still the same.It came complete carb,dist, every thing was set on dyno ? it has a chrysler dist. I tried to call Indy twice but they pass me off afew times and then they say they will call me back.I would like some advice where to start troubleshooting at . like i said i have already swap card and checked air gap in dist. checked orange box and made sure of good gound . i have not moved timing i checked it at 2000 rpms and it checked out to be 38o any advice would be welcome.

Sounds like the advance springs are too light or its sticking in the advance position,vacuum leak my cause that too

Thanks for your reply
500ciDuster
this is what i found to be the problem. the distributor shaft is spline together under the weights it has striped out the splines.
brand new dist ?

Cool, sounds like it needs one or new parts

Paging Josh King, please answer the peach phone...