the engine starts and immediately revs up to 3000rpm and then looses rpm and dies. If i try and keep it running and give it gas right before the rpm's get too low it'll rev back up to 3k jbut if the rpms are too low it stutters and shoots a flame out the carb. I was told it could be the power valve burned out. The carb is a speed demon 750 vacuum secondaries (no choke).

 

Have you done any work on it recently. It may be timing but a power valve will cause weird problems.