OK, here is the thing, and I know how much of a pain this is because I have numerous IDI's with manual transmissions. I'm going to guess that you have the black plastic hydraulic line and not the red semi-translucent hydraulic line. You have air trapped in that hydraulic line. Believe me, you really will have a devil of a time getting it out if you can't see the air bubble, and it doesn't have to be a big one. The truth of the matter is, that the neither the slave cylinder, nor the master cylinder can move enough fluid through the line, to push that bubble far enough to get it unstuck. If you had a way to put your whole truck on like a giant rotisserie, and spin it once around, your problem would be gone. But we can't do that, so we have to resort to various tricks. There are a few things you can try. Mess around with that plastic line A LOT. Bend it as much as you dare, trying to get a straight line up to the master cylinder. Don't mess with the bleeder screw, as it is just about worthless. Push the fork all the way forward with every new position of the line, and let it out S L O W L Y. You can also try vibrating the line while your doing this. I'm not going to make suggestions about what you can use to do this, but you need to oscillate that line at a high frequency to break the bubble up and get it to move. Perseverance will prevail. Always keep the lid off the master cylinder, and always make sure it stays full.