I have a 700r4 in my GMC Jimmy 6.2 Diesel. It has a transmission that was "GM Certified" rebuilt...it has burned the 3-4 clutches twice. The TV cable is adjusted correctly; however pressure is a constant 120 PSI in all forward gears and over 200 PSI in reverse (my gauge only goes to 200). Pressure does not change when the TV cable is pulled or when the engine is accelerated. Any ideas? I'm thinking it's a stuck boost valve? Both times the clutches burned the transmission was under a heavy load...hauling a trailer and when engaged in 4WD while in snow.