...How about you check and see how high you can get the engine against the converter ? Warm it up thoroughly then mash the brakes and then see how high the engine will go in first gear. A real 340 converter in your package should get you around 2600 to 2800 stall. If not then likely your stator overrunning clutch is failed in the converter. Or it's not a real 340 converter. A failed stator ORC will run down the road fine but make the car lazy off the line....