I have a Rheem RRPLB024JK08E outdoor gaspack, 5 months. Old. It locked itself out, red lights indicate high limit open. Put in new high limit switch, no change. After I reset it (kill power) it works fine for about 8 or 10 cycles. Then, draft inducer comes on... burners ignite and stay on, but no blower. It will continue to lock out if I don't reset it. The guys who installed it found nothing, but of course, it worked fine when they were here.

Sounds like the logic in the blower control board is bad.

I agree, it's very likely the ignition control board. If you want a second possibility it might also be something as silly as a loose connector or wire to the blower motor.