Please don't confuse tq lockup with a shift into 4th gear. They are two seperate items.

Shift from 3 to 4 should reduce rpm by ~1,000
Torque converter lockup should reduce rpm by ~200-500rpm.

If you keep steady pressure on the throttle and lightly tap the brake (just enough to kick on the brake lights) the tq should unlock. That's the quick easy way to see which it is.