I have a Goodman furnace and when it first lights everything works fine. When the furnace comes on the second time it acts as though the center heat exchanger is clogged and I get a flash back shutting off the rollover limits. I have tried blowing the center tube out. What do I need to do to correct this.

Probably replace it,, but first give more details like the model number,, what are you thinking it is stopped up with?, possible bad/cracked heat exchanger