D-Teck DT76301 installed 4-30-2009 in a chev 3500 diesel, pulling hill 4th gear with #4200 sudden change of power, black smoke out exhast, kept driving till found safe spot to pull off, when I put the clutch in the engine reved up max RPM shut down engine checked every thing under the hood oil water ect every thing looked ok, started the engine again, full RPM again,