If it shifts hard at high RPM with vacuum unplugged, then there is no need to do the control pressure test. The trans is working correctly. That means you have a problem with your VRV. Put a gauge on the output side, and start the truck. You should be seeing between 15 and 18 hg of vacuum. If you see more, loosen the VRV and back it down to 15hg. Then run the throttle, the vacuum should drop as you rev it up. If it doesn't, the VRV is bad. Even at 15hg, it might still shift a little slow, don't be afraid to back it down until it shifts where you want.
As to the control pressure test, sorry it's a pretty crappy scan, but you hook up a hydrolic pressure gauge to this port (fig 6) and hook a vacuum pump up to the modulator. Pump up to 15hg, shift to all positions, record pressures. Drop vacuum to 10hg, rev to 1000rpm, shift all positions, record pressures. Drop vacuum to 1hg, keep at 1000rpm shift to all positions, record pressures. Needless to say, chalk it, parking brake, and stand on the brake while doing the test.
