Almost sounds like the coverter is locking. Did you try reinstalling the EVO?
02 F250. Turbonetics, SRP1, Tim from P.I.S built Hybrids, Built Trans, Afe Stage 2, HPX line. Tuned by Jonathan from Beans, 4 inch exhaust, with the muffler. Triple Phantom 2 gauges. Forged Rods and with another block. 500hp.